Object is a stable API with API state '&3'.

What causes this issue?

You are about to delete an object with API state '&V3&' which guarantees
stability for consumers as defined by compatibility contract '&V4&'.

System Response

In general, deletion of objects with this API state is not permitted.

How to fix this error?

Don?t delete this object, if the object has already been shipped
together with its API state.
Otherwise, you can remove the API state by clicking ?Delete...? on the
?API State? tab of the object?s ?Properties? view. After that, you can
delete the object itself.
For more information about API states and compatibility contracts, see
www.help.sap.com> SAP S/4HANA > Product Assistance > English >
Enterprise Technology > ABAP Platform > Developing on the ABAP Platform
> Application Development on Application Server ABAP > ABAP Development
Tools ? Eclipse. > ABAP Development User Guide > Concepts > Released
APIs.

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.