Martinyoung is correct. To put it slightly differently, the front sprocket bolt is a regular "lefty-loosey, righty-tighty" type fastener. It also probably has the highest torque spec of any fastener on the bike.
Easiest way to get it off is to put the bike in gear, have someone else hold the rear brake pedal down, & go at it with a longish breaker bar.
I had a little incident with my first bike that involved the chain snapping as I came off a stop light. To remove that sprocket, I had to attach the old chain to a piece of 2x4 in order to keep the driveshaft from moving. That was fun! (Umm, not.)