I have this model with a 1 piece rubber grip. There are no screws on the grip it's just a friction fit. Is there a special tool or a trick to remove this grip?

If you have the grip that I think you have, yes there is a tool - but you can most likely get by without one.
1 clear the chamber
2 remove the magazine
3 check the chamber again
4 put a finger up into the grip and flex the front edge of the grip out a bit
5 use your other hand to get a grip on the flexed out portion and begin the removal

Is this the E2 grip? If so if should come with a tool that makes it easy to pry off one side. Sig would send it to you I am sure.

Thanks ZSMichael. That is the grip I have. The video explains the process very well.