How to replace lens of Yi 2 4k action cam

Actually, I attached non-distortion lens and show how to detach lens rim for replacing lens of Yi 2 4K action cam. 

Action cam with non-distortion lens 50mm 

Using screw driver make some space between body and lens protection rim. 

It needs more power to detach protection rim. It is very hard to make few scratches on lens rim. 

Now, I replaced 155 degree stock lens. 

Done