Funds center &1 in FM are &2 cannot be deleted

What causes this issue?

You tried to delete funds center &v1& in FM area &v2&.

How to fix this error?

If you want to delete the top funds center from a hierarchy, you can
only do so in <DS:TRANS.FM2H>graphic hierarchy maintenance</>.
If the funds center you tried to delete was not the top one, a
technical error has occurred. This error cannot occur if you delete the
funds center using <DS:TRANS.FM2H>graphic hieararchy maintenance</>.

Error message extract from SAP system. Copyright SAP SE.