Assuming you mean the primer BULB, the ring that surrounds it has 2 lugs at 9 and 3 o'clock. They have to be compressed inwards. The ring then comes out, followed by the bulb.
It's fiddly - but possible - using a pair or screwdrivers. Briggs sell a special tool that does it in about 5 seconds.
phil_saunders(a)bigfoot.com
Phil Saunders
October 2010