[endgame]

From your Transaction Screen you can use the pulldown to see various groups, e.g. AA, Waivers, DFA, as well as 40-Man roster. I usually keep this one in the upper right corner where, I think, it is by default. If you want to remove someone from the 40-man (from that box) you can simply drag him to the bottom of the screen, after which a box will pop up asking you if you want to put the player on waivers and DFA.