Is my disk locked in a permanent way?
Vous devez add the override option:
delete partition override
override
Enables DiskPart to delete any partition regardless of type. Normally,
DiskPart enables you to delete only known data partitions.
Source DiskPart Command-Line Options
Comment delete an OEM partition
"Cannot delete a protected partition without the force protection parameter set."
This is a warning from Windows that vous devez be doubly sure that
you want to delete this partition.
If you see this error when trying to delete a partition then use:
delete partition override
Source Comment delete an OEM partition