Usually you will see screws on the edge of the pick guard. You need to unscrew these after removing your strings. Some guitars do not have pickguards, like that of a jackson.
If it is an electric guitar, just unscrew the pickguard. If it is an acoustic guitar, warm it gently with a hair dryer, as you take it off gently with your nails or fingers.
You see screws all areound the pickguard?after removing the strings,pulling the knobs off and removing the selector switch head.your pickguard should come off with little to no trouble.