This Instructable will explain how I made some slicks for one of my bikes. You can do the same, just remember to wear appropriate safety gear, (A glove and a breathing mask as a minimum, a plastic raincoat would also be recommended.)
Step 1: Tools and equipment.
To do this you will need some type of directional sanding tool, by which I mean either a belt sander or an angle grinder with a sanding pad like I used. You will also need a straight and true front wheel that matches the tires you want to sand and a bike flipped upside down so you can use the forks as the wheel mount. Probably best to use a bike you don't care as much about as it will get messy as shown in the photo, the rubber does however easily hose off.