You need a small, flat blade screwdriver (like a jeweler's screwdriver), or else a chip-puller, or perhaps a small putty knife.

Carefully, and slowly, pry up the edges of the CPU from its socket - the CPU is the grey-purple ceramic bit, and the socket is the black plastic bit.

The trick is to work all the way around all four sides, being firm but gentle, doing it gradually. You want to avoid popping one side out violently, as that will bend the pins. They can be bent back, but it's a big PIA.

Best,

Matt