Yes you can. Obviously you'll be at a reduced power level, but no problems should occur from doing this.
EDIT: While I believe this is a "plug on" application, you'll want to ensure your coil is not connected either. I doubt it will be down in the hole, but you don't want to have the coil attached to the wiring harness without it being able to throw electricity to ground somehow ... you'll burn out the coil doing that. Please also note, your dash light will light (check engine light) when you start. You will get some error about a misfire. When you get this fixed, you'll want to clear the codes. Also, consider taking the truck to a machine shop or a good mechanic's shop which deals with Fords. They will have dealt with this problem before, undoubtedly.