The easiest way I know how to do it is like this:
1. Take a small flathead screwdriver and gently pry up the small gray pins going thru the clasps. It'll only come a little ways, but that's fine.
2. Take a set of needle-nose pliers and gently press the ends of the clasps on the bottom side of the board. This will cause the pins to back themselves out.
3. Once all the pins are completely out, gently squeeze the clasps again with the needle nose pliers and push up. You'll have to do this one corner at a time.
4. Once all the clasps are pressed and over the hooks, you can just pull it out.
*Be very careful with the screwdriver and pliers. Don't push real hard, you don't want a hole in your board. If you have any other questions just let us know.