You cannot delete class here: assignments exist

What causes this issue?

You can only delete a class with allocations using the function
<LS>Edit -> Special functions -> Delete class w. vals</> from the
initial screen of a class maintenance function.

System Response

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

How to fix this error?

If you want to delete a class with allocations, choose the function
above or start report <ZH>RMCLKDEL</>.
If a large number of objects (> 50) is allocated to the class, run the
program in the background to avoid timeouts.

Error message extract from SAP system. Copyright SAP SE.