The waiver claim page has been updated such that if you have 50 players and wish to make a claim, the system will prompt you for who to release if your claim is successful. When your claim is processed this player will be released to waivers.
To note: until this is tested to be working perfectly, which won't happen until (1) a player clears waivers unclaimed, (2) a player is claimed and the team does not have 50 players, and (3) a player is claimed and the team has 50 players, please post all claims (and players to be released if necessary) to the forums as backup.