2005 Chevy Avalanche Bed Liner Removal

I recently purchased an 05 Avalanche, while cleaning the truck out, i noticed beach sand in the bed and as i was spraying it out with a hose the sand kept coming from between the bed liner and the bed. Its a plastic bed liner and i was wondering if there is a special tool required to remove the bed liner so i can completely clean the back of the truck. On the bed liner, it looks like where screws should be there are plastic covers that have three indentions where maybe a special tool is required to remove them, they do rotate, but any ideas?