Access needs these tables in order to manage the objects you created in the database. You cannot (and should not) delete these tables nor alter their content manually. If they get corrupted import all objects into a new database.
Are you talking of "garbage" created by the incremental writing feature? It will grow larger as you keep modifying the database. A simple compress database run should get rid of it, sometimes a /decompile helps some more as well (not supported function, make backups before using).