Field is already in use. Specify a calculation formula

What causes this issue?

You attempted to delete the calculation formula for a local field, but
this field is already being used in a query and must therefore contain
a calculation formula.

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?

Define a calculation formula for the field.

Error message extract from SAP system. Copyright SAP SE.