Deletion not possible; &1 assigned to matching group &2

What causes this issue?

You cannot mark matching type &V1& for deletion. The matching type is
assigned to one or more matching groups that have not been marked for
deletion.

System Response

The system automatically ignores the deletion request. The selected
entries remain unchanged.

How to fix this error?

All assignments to all groups must be deleted before a matching type can
be deleted.
If you still want to delete this matching type, go to matching group
&V2&, and delete the matching type assignment for matching type &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.