MapDB: How to remove a HashMap?

Question

I have a MapDB with multiple HashMaps.

 DBMaker.Maker mapmk = DBMaker.fileDB (this.dbfile);
 DB mapdb = mapmk.make ();

 HTreeMap <String, String> map1 = mapdb.hashMap ("abc").createOrOpen ();
 map1.put("max", "123");

 HTreeMap <String, String> map2 = mapdb.hashMap ("def").createOrOpen ();
 map2.put("sam", "098");

 HTreeMap <String, String> map3 = mapdb.hashMap ("ghi").createOrOpen ();

How can I remove a whole map (e.g. map2 = "def") with all its key/value-pairs from the DB?