Done with Ubuntu? Removing a dual boot the wrong way leaves a PC that boots to a GRUB error. Removing it in this order — boot entry first, partitions second, space last — leaves Windows starting exactly as it did before Ubuntu ever arrived.
Everything on this page happens from inside Windows, and the order is the entire secret. If you delete the Ubuntu partitions while the firmware still tries to boot Ubuntu first, the PC greets you with a GRUB rescue error instead of Windows. So: make Windows the default again, remove Ubuntu's boot entry, then delete its partitions and reclaim the space. Back up anything stored inside Ubuntu before you begin — once the partitions go, its files go with them.
Before anything is deleted, tell the firmware that Windows is in charge again. Restart into the BIOS setup — from Windows, Settings, Recovery, Advanced startup, then UEFI Firmware Settings — open the Boot section, and move Windows Boot Manager to the top.
Only when Windows starts cleanly on its own is it safe to remove the Ubuntu pieces. If your BIOS offers the option to delete the ubuntu boot entry outright, you can do it there — but the folder cleanup in the next step is still needed.
Ubuntu keeps its bootloader in a folder named ubuntu inside the small EFI System Partition, next to Microsoft's own folder. Windows hides this partition, but an admin Command Prompt can mount it long enough to clean it.
mountvol S: /S — S is just a free letter; use another if S is takencd /d S:\EFI and look around with dir — you should see folders like Microsoft, Boot and ubunturmdir /s ubuntu and confirmmountvol S: /dBe precise here. The Microsoft folder in that same partition is what boots your Windows — it must not be touched. You are removing one clearly named folder, nothing else.
Now the space itself. Open Disk Management with diskmgmt.msc. Ubuntu's partitions are the ones with no drive letter and no file system name that Windows recognises — Windows files live on the lettered NTFS drives, which you leave alone.
Take ten seconds per partition to be sure. The EFI partition (a few hundred MB, labelled EFI System) and any recovery partition belong to Windows and stay. When in doubt, compare sizes with the layout you remember from the installation.
With the space unallocated, hand it back to Windows. Right-click the C drive in Disk Management and choose Extend Volume, then accept the full amount offered.
Restart once at the end and confirm the boring result you wanted: power on, Windows loads, no menu, and the C drive shows its original full size.
On a genuinely old PC where Ubuntu was installed in legacy BIOS mode, GRUB may live in the master boot record itself instead of the EFI partition. There the cleanup is a Windows command, run from a Windows installation USB or the recovery environment.
bootrec /fixmbr to restore the Windows boot codebootrec /fixboot as well if the first alone is not enoughMost Windows 10 and 11 machines are UEFI, where the folder method above is the whole job. Use this step only when your machine truly boots in legacy mode.
Thinking of trying Ubuntu again later? The video shows the complete installation whenever you are ready.
▶️ Watch Full VideoNo. Ubuntu lived in its own partitions and its own folder in the EFI partition. Deleting exactly those returns the disk to its previous layout, and Windows, its programs and its files are untouched. The only files lost are the ones stored inside Ubuntu itself, so copy those out first.
That means the partitions went before the boot order was changed, so the firmware is still trying to start the deleted GRUB. Boot a Windows USB, open the recovery Command Prompt and rebuild the Windows boot files — and set Windows Boot Manager first in the BIOS order. Your Windows installation itself is unharmed.
Disk Management can only extend a partition into unallocated space that sits directly beside it. If a Windows recovery partition sits between C and the freed space, Extend stays grey. That is a Windows limitation, not a failure of the removal — a partition tool can move the recovery partition, or you can simply leave the free space as a separate data drive.