Hi,
If the material docs are posted against a material with serial number profile, you cant delete the serial number profile from the material master. Instead, you may change and assign a new serial profile with different / no number assignment.
You may check the following note: 71997 - MM02 - Change/delete the serial number profile
403404 - Plant-specific deletion of serial number profile
If you want to delete serial number profile itself from customizing, then you should not delete any dependent profiles.
If you are asking about deactivating lock against serial number internal assignment, the deactivation is to allow different users to create serial number for the same material at the same time.
Regards,
AKPT