I always turn the firing button to the "locked" position then just pull it off with my finger/thumb, but perhaps mine is a bit worn and easier to remove than a new one. Anyway, the big fire button is certainly one thing you want to remove ahead of bath time.
One of the first things I do when bathing the REO is run hot water down
through the fire button area while moving it from "locked" to "unlocked" with the REO right-side up and then upside down 'til my fire button presses down easy and goes from "locked" to "unlocked" very easily/smoothly.
Norman