Data record contains fix value from BC Set and cannot be deleted

What causes this issue?

You have flagged a data record for deletion which contains at least one
field which is flagged as fix by a BC Set activation. You can only
delete this data record after you have released the BC Set fix values
in the 'BC Set: Change Field Value' menu.

System Response

The affected data records are not deleted. Any other data records
flagged for deletion are deleted.

How to fix this error?

To delete the locked data records, choose 'Edit' -> 'BC Set' -> 'BC
Set: Change Field Value'.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.