Not possible to delete basic line & (alternative line & exists)

What causes this issue?

You have attempted to delete line <(>&<)>. This is not possible because
this is a basic line for which the alternative line <(>&<)> is included
in the service specifications.

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?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.