So you wanna get rid of the new WOD models? thats fine, they might cause crashes and some are glitched.
How to:
1.Find the world of warcraft folder usually in C:\ProgramFiles(86)\Wrath of the Lich King 3.3.5a
2.Go into data and remove patch-w.mpq
3. Go into EnUS (or EnGB etc..) and remove patch-EnUS-w.mpq
4. Launch the game and you should see the old models!
Hope you found this useful!