I replaced a copy of Windows 10 with Ubuntu 18.04 desktop successfully. The only problem that remains is that the Windows 10 boot selection entry still appears. I know that disabling the OS probe will work around the problem but I would prefer to get rid of whatever is causing OS probe to think that Windows 10 is still there.
EDIT: I am going the other way than what was suggested in the comment. I overwrote the Windows partition with an ext4 bootable partition.
Any ideas on how to do this?