Most ambi's are held on by the right grip panel.
Take it off, and the right safety lever should pop off with a little light force.
After that, the other one comes out just like a normal 1911 safety.
The other way it is done uses an extended disconnector/sear pin with a small slot in it which sticks out the right side of the frame.
This secures the right lever.
Remove the slide.
Remove the left lever as you would any M1911 and then rotate the right lever up and out of the pin slot.
rc