Removing fields could impede Customizing

What causes this issue?

You are removing a field in the field list for the general budgetary
ledger Derivation Tool.

System Response

The system issues a warning.

How to fix this error?

After removal, this field will not be shown anymore as a source field in
the Derivation Tool. You can work with derivation rules previously saved
, but not use this field for the creation of new rules.

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.