System &1 is marked as an SAP (R/3) system; deletion is problematic

What causes this issue?

Data (such as orders or stocks) is to be deleted that might have been
transferred from SAP R/3 or a different SAP system. A deletion could
lead to data inconsistencies because the deletions are not distributed
to these systems or are not permitted there.
This message can also be displayed if the logical system used is not
entered as an SAP
R/3 or other SAP system and another system exists in the same
system group (&V2&) that is an SAP R/3
or other
SAP system. In this case, the deletion of data (such as planned
independent requirements or stock) can also have an effect on this SAP
R/3 system. For example, if stock was transferred from an SAP
R/3 system,
a deletion can lead to data inconsistencies between SAP APO
and SAP R/3 (because the stock data in SAP R/3 and SAP
APO differs).

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?

Check your scenario and the settings for the logical system.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.