User &1 is entered as the Changed By user in change documents

What causes this issue?

Change documents still exist for changes made by this user.

System Response

The user cannot be deleted until there are no longer any change
documents in the database changed by this user.
The change documents are usually archived or delete using the delete
processes of the logged application data.

How to fix this error?

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

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.