How to Fix: Windows 10 Installed Twice (32 bit and 64 bit)

Dennis Faas's picture

Infopackets Reader Gros C. writes:

" Dear Dennis,

By mistake I installed both Windows 10 64 bit and Windows 32 bit on my machine. Both installations reside on separate partitions. I want to keep the Windows 10 64 bit, but the problem is that I don't know how to safely remove the Windows 10 32 bit from my machine. Can you give me a bit of advice on how to remote Windows 10 32 bit? "

My response:

This can be very, very tricky, as how to remove Windows 10 32 bit (or even the 64 bit version) on a separate partition depends on which installation of Windows contains the master boot record.

For example, if you first installed Windows 10 32 bit on the C drive, and then you installed Windows 10 64 bit on another partition (the D drive), the master boot record (MBR) for both operating systems will reside on the Windows 10 32 bit partition because that is the first operating system you installed. It's also because only one partition can be set as "active" and "boot", which then provides you the option "Which operating system do you want to boot?" during the boot process.

If you were to remove the C drive partition (for example), the computer would no longer boot and you would not have access to either operating system. You would then have to modify the D partition and set it as "active" and "boot", then reclaim the space from the C drive and assign it to D - assuming that is what you wanted to do.

While I can't provide exact step-by-step instructions on how to remove an operating system from a dual boot / multi-boot system (because there are MANY variables to consider depending on the setup) - I will provide a general 'how to' below.

How to Fix: Windows 10 Installed Twice (32 bit and 64 bit)

  1. First, backup your entire system using a disk image and create rescue media. If you screw something up, you can boot from the rescue media and use the disk image backup to recover the entire hard drive or specific partitions. Depending on the size of your drive and how much data you have used, you may need to save the backup onto an external drive.

    Oftentimes, when I'm working on a system using my remote desktop service, what I'll do is split the hard drive into another partition (called the "Internal Backup" partition) and use that for creating an image backup of the entire system. This alleviates the need for backing up onto an external drive (especially if you don't have one, as they cost money). Let's look at an example: if your hard drive is 1 TB in size and your C and D drives are only taking up 150GB each (totaling 300GB out of 1,000 GB), it would certainly be possible to create a third partition (the Internal Backup drive) - let's called it the "Z" drive; you could then image all partitions (boot partition, C and D, etc) onto Z.

    Note: if you don't know how to create a proper disk image, you are welcome to contact me for 1-on-1 support using my remote desktop service.
  2. Next, use the Windows Media Creation Tool to download your current version of Windows (8 or 10) in ISO format. Once you have the ISO file, burn it to DVD or USB thumb stick - this will make the CD or USB bootable. Once the CD or USB is booted, you can then repair your master boot record from the Windows Setup.

    To make the ISO bootable on USB, use Rufus. To burn the Windows ISO file to DVD, I suggest using CD Burner XP (using the ISO option).

    Note: if you have Windows 7 or Vista the Media Creation Tool won't be available; in this case you will need to download a third party tool to fix the master boot record manually. One such option is the "Boot-Repair-Disk" at sourceforge (free).
  3. Next, download and create a bootable MiniTool Partition wizard CD version 9.0 or 9.1 - these are the last free versions of the MiniTool Partition Wizard bootable CD (version 10 is not free). Search Google for "pwfree9.iso" or "pwfree91-x64.iso" (64 bit) or "pwfree91-x86.iso" (32 bit). At the time of writing, all free versions of MiniTool Partition Wizard CD are available here. If you don't have a CD or DVD drive for your system, you can use Rufus to write the ISO file to USB thumb stick.
  4. Next, boot from the version of Windows you want to keep (the Windows 10 64 bit, presumably). When you get to the desktop, go to "My Computer" or "This PC" and locate the C drive. Rename the C drive to "Windows 64 bit - DON'T DELETE" or such, so you don't accidentally delete the wrong partition in the proceeding steps.
  5. Next, reboot the computer with the MiniTool Partition Wizard CD / USB. If the CD or USB doesn't boot then you will need to modify your BIOS boot sequence and place the CD or USB drive in the #1 boot sequence (above the hard drive).
  6. Once MiniTool Partition Wizard is loaded, locate the hard drive partition you want to delete, then right click it and select "Delete". If you want to re-arrange the partitions to reclaim space, now is the time. Once you have everything set, click to Apply the changes from the top menu. Once you do so, there is NO going back (unless you recover from disk image).
  7. Once that is done try booting from your computer. If it boots then you are good to go, though you will likely need to modify your Boot Options using msconfig or bcdedit to remove the old operating system from the boot options menu. If you receive "operating system not found" error on a black screen, reboot the computer with the Windows DVD or Sourceforge "Boot-Repair-Disk" and repair the master boot record. This should make your computer bootable again - fingers crossed!

At this point everything should be working - however, if you are not sure about any of the steps (which could leave your computer unbootable), you are welcome to contact me for additional support, described next.

Additional 1-on-1 Support: From Dennis

Deleting partitions and modifying your master boot record is NOT for the faint of heart. This is fairly technical - if you don't know what you're doing, or are second-guessing yourself at any of the steps I've listed above, you are welcome to contact me for 1-on-1 support using my remote desktop support service, where I can manage this for you. Simply send me a brief message describing your issue and I'll get back to you as soon as possible.

Got a Computer Question or Problem? Ask Dennis!

I need more computer questions. If you have a computer question -- or even a computer problem that needs fixing - please email me with your question so that I can write more articles like this one. I can't promise I'll respond to all the messages I receive (depending on the volume), but I'll do my best.

About the author: Dennis Faas is the owner and operator of With over 30 years of computing experience, Dennis' areas of expertise are a broad range and include PC hardware, Microsoft Windows, Linux, network administration, and virtualization. Dennis holds a Bachelors degree in Computer Science (1999) and has authored 6 books on the topics of MS Windows and PC Security. If you like the advice you received on this page, please up-vote / Like this page and share it with friends. For technical support inquiries, Dennis can be reached via Live chat online this site using the Zopim Chat service (currently located at the bottom left of the screen); optionally, you can contact Dennis through the website contact form.

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