Deletion of object &1 is not possible; object is still being used

What causes this issue?

You tried to delete object &v1&, but object &v1& is still being used in
other objects of the Business Rule Framework (BRF).

System Response

You cannot delete.

How to fix this error?

Call object &v1&.
Call up the where-used list. To do so, choose @3A@ with the quick info
text <ZK>Where-Used List</>.
Delete the corresponding usages.
Delete object &v1&.

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.