I've been told this is the procedure. Never tried it myself. Good luck!
- Position armrest straight up.
- Push the armrest in (towards the seat back) by applying pressure at the pivot point.
- Still holding it pushed in, rotate it to the rear as far as it will go (if you do this right, you'll see that will rotate much farther to the rear than normal).
- Now pull the armrest out of the seat back.