What type of treatment is done for a hoarder to make him more normal and get rid of all his excess stuff?

Hoarding. Treating underlying obsessive compulsive disorder, both with psychotherapy & with medications, does help. Also psychological testing is sometimes needed to check for IQ & personality profile.
It's a hard one. Well, hoarding appears some sort of obsession, so treatment usually prescribed for obsessive compulsive disorder might turn out helpful. Behavioral/cognitive therapy and anti-depressants used for obsessive compulsive disorder might be of help.