Can anyone tell me how to reverse a dual boot system.
Installed with GRUB.
I have linux mint and Windows 10 on dual boot.
All I want is to have them single again.
There must be some way to do this?

No idea what you're asking; if you just want one OS on the system, just delete the one you don't want. Want to keep Windows? A Microsoft forum can tell you how:
https://answers.microsoft.com/en-us/...2-421a1d072fa4

Want to keep Linux? Delete the Windows partition, and edit the grub menu to remove the reference. Much like your other threads, where you don't ask a clear question or provide much information:
https://www.linuxquestions.org/quest...as-4175692687/
https://www.linuxquestions.org/quest...as-4175682958/
https://www.linuxquestions.org/quest...up-4175690505/

1 members found this post helpful.

By definition, dual boot means exactly two operating systems installed on a single computer. If you don't want dual boot, you must cut the number of installed operating systems to less than two.

If what you're looking for is to have a computer boot directly into one operating system without a pause to choose which installed operating system to boot, there are ways. One is to reconfigure the operating boot loader with a timeout value of 0 for the default installation. Another is to install each operating system on its own disk, with each system's bootloader configured to ignore other disks and operating systems, then choose the default operating system which will boot without pause via a BIOS boot priority setting.

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Thank you for the answers.
No idea what I am asking, simply this.
Windows 10 on boot up and Linux mint boot up from usb.
Like it was before I got mint to install with dual boot.
Thats it in a nutshell.

So back to what you were told previously: delete the Linux partition from your hard drive, and restore the Windows default boot manager. Did you not read the first response, or the accompanying Microsoft article about how to restore MBR back to default??

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Take the computer to someone who can successfully Google:That would have been a much better thread title.
And Google is much less emotional than people on internet fora.

P.S. You can use the edit button on your post #1, to change the title, to make this useful for future searchers. You actually want the opposite of "dual boot".

Don't touch. Shrink only Linux partition. As much as you can. Don't remove Linux, don't remove grub - you may will end with not bootable Windows. Grub to boot requires access to its modules on Linux partition. You just made wrong decision to run dual boot system instead of to create virtual machine. The other solution is to install very basic Linux installation only for purpose to boot Windows. All such installation may take 500 MB.

2 members found this post helpful.

Maybe restore windows bootloader before removing linux.