habe eine Lösung für dich gefunden , ist aber in englisch.
Delete the anonymous user
-In the Filezilla server window, from the pulldown menu choose Edit->Users to get the "Users" Dialog box.
-In "Users:" area on right side, highlight "anonymous".
-In the middle area, under "Account settings", uncheck "Enable account"
-Click "OK" to close the "Users" dialog box