I'm preparing a USB installer to perform a clean installation of Windows 11 after a suspected malware incident. Windows Setup is showing several partitions and I'm unsure which ones are safe to remove. Which disk should I select, and what should the partition list look like before I continue?
3 Answers
Back up anything important and verify that the backup can actually be opened before deleting partitions. You generally don’t need a separate disk-wiping utility for this installation; deleting the partitions on the correct target drive and installing Windows over the unallocated space is sufficient for a normal clean setup.
For a true clean install, Microsoft’s usual process is to remove all partitions from the target Windows drive and install to the resulting unallocated space. Be extremely careful if the computer has multiple physical drives—check the drive sizes and labels so you don’t erase a drive containing important data.
If Disk 0 is the internal drive you want to erase, delete each partition listed under Disk 0. Continue until it appears as a single block of unallocated space, then select that space and click Next. Do not delete anything on the USB installer, which may appear as Disk 1. This will erase every file on Disk 0, so confirm your backups first.
The safest layout before installing is Disk 0 showing only unallocated space, with the free space and total space matching. Then select that unallocated space and let Setup create the required system partitions automatically.