standard ford radio removal tool... about $5-6 from walmart. looks like a u shaped wire. has small spade tips that is meant to catch into the release bracket. once both sides are in the holes in the radio, push the tool outwards and pull. radio should slide right out easily...
if your radio doesn't have the 4 holes in the faceplate, but has slots instead, then you use the radio keys. it's also included in the tool kit you buy.
pic borrowed from internet:
more instructions here: