Summarize this article:

With the knobs unscrewed, the action is free to move. Grab 2 of the brackets from the top and pull the action forward until it reaches about a 45-degree angle. Then lift straight up to remove it. If you want to keep the action in good condition, only lift from the brackets, because touching the internal mechanism could cause damage. If you are planning on scrapping the piano pieces, then don't worry where you grab to lift the action out. Having another person to help lift the action out is a good idea because the action could be unexpectedly heavy.

Summary:
Pull the action mechanism forward and the lift it off.