Leider finde ich auch in Aktuellen Update 2021 nicht die Funktion um die Liste der "Zuletzt verwendet Dateien" zu löschen in der Deutschen Version. Adobe Photoshop Elements Version: 19.0 (20210126.m.155261) x64
Set your preferences in the following menu:
Edit >> preferences, second options line, "saving" and choose the number of recently used files to keep.
I did a short test, and it seems that setting it to zero will do what you want.
(and don't hesitate to write in German: if other members don't understand it, they use the online translator).
I believe the list will be deleted if you reset the preferences file. Go to Edit>Preferences>General tab and click the Reset Preferences on next launch button. All other preferences you have chosen will also be deleted.