Unscrew the 4 screws securing the rear lens guide. Carefully remove the guide, making sure not to lose the spring that connects the three(or two) pieces. Keep these pieces together.

Locate the two contact points on the rear lens rings. You may need a special tool('井') to loosen these points, such as a small screwdriver or tweezers may be okay too(I haven't tried).

Remove the lens barrel, ensuring that the other two barrels remain in their original positions. Misaligning these barrels can be difficult to correct.