How can I remove an erroneous field from dropdown list

How can I remove the field "%OPUS%" that I erroneously created ant that appears in the dropdown list ?

Thx

Select it and press Shift+Delete
It's probably necessary to choose another field and enter something and press the OK button in order to confirm the deletion and then finally restart the program.

Where should I choose it ? It the dropdown list in action / replace ?

Yes...