Yes. But do you really need to remove the stock belts? I kept mine.
When I first installed my 5 point Simpson harness, I kept the stock seat and stock belts. I use the stock belts when driving on the street. At the track I would use the harness and get the warning light. I was playing around with the idea of making a dummy seat belt clasp to put into the recepticle to fool the car into thinking the seat belt was fastened. But then I replaced the stock seat and the problem went away. Turns out that the stock seat has a computer in it that controls the seat belt monitoring function. Without the stock seat, I never get the warning light any longer, even when I'm not wearing the stock belts.