This function is not allowed in the standard hierarchy

What causes this issue?

You are directly processing the <DS:GLOS.standard_hierarchy>standard
hierarchy</> (cost centers, business processes). The following actions
are invalid for individual values:
Inserting groups that already contain values
Removing/deleting groups that already contain values
You are processing the profit center standard hierarchy or any other
alternative hierarchies that contain parts of the standard hierarchy.
The following actions are then invalid for individual values:
Delete
Insert
Reassign (delete and insert)
Removing groups that already contain values
Inserting groups that already contain values

How to fix this error?

Undo the change you wanted to make.

Error message extract from SAP system. Copyright SAP SE.