Deleted application objects - Upgrade question

Hi All, To delete all the DEL_ objects, it is necessary to uncheck there a configuration key ( Keep Update objects 4.0, Keep update objects 4.1) then DAX will resynchronize the DB and drop those obsolete tables and fields. Unfortunately it did not work. So, the question is how or what to do to get rid off ‘DEL_’ objects? Why using configuration they configuration keys doesn’t work?