they have a tool designed to pull it out from Alliance-speed queen. But if you dont have the tool, I would put on a pair of gloves and pull it out with your gloved hands. Wedge your fingers underneath the agitator and pull straight up. It takes some brute force, but it comes off.
If you have access to a dryer belt (the long serpentine type), drape it over your shoulder and under the agitator. Then you can use your back and leg muscles to do the "pulling" (up that is). It's a heck of a lot easier on the fingers but you may want a buffer between the agitator and your chest when the agitator pops up.
We all assume it is not a wa series! You an use 2 stright claw hammers, or thin prybars with the 90 degree on them,. Slip under the aggitator across from each other and twist them up to pop the thing off. When using the finger/glove method wear a football helmet w/ mouth guard been there done that.