Diskpart - Can't delete a partition without the force protected parameter set

Is my disk locked in a permanent way?

You need to add the override option.

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

How to delete an OEM partition

"Caot delete a protected partition without the force protection parameter set."

This is a waing from Windows that you need to 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 How to delete an OEM partition