they are a free agent to sign onto a practice squad of their choice, and even negotiating a signing bonus or more pay if they have veteran status.
During waivers any team can claim the player (based on draft order of priority) but they Must put them on their 53 man roster (for at least 3 weeks) If that team wants to out them on their practice squad once again they would have to be cut, go through waivers, then resign as a free agent to said practice squad.
Also any player on a practice squad can be claimed by other teams but they have to be placed on the 53 man roster (at least 3 week) to be picked up.
So there is some Risk for the team releasing a player they may not get them back onto their practice squad.