I’m not sure what the rules are, but what happens if a player refuses to play for the team that drafted him? I’m sure he’ll be a professional and play for whoever picks him, but for argument sake, let us pretend he openly claims “I won’t play for anyone but the Packers.” What then?
The team that drafted him retains rights to the player until the following year’s draft, at which time the player is eligible to be picked again. The team that drafted him and holds his rights may trade the rights to the player to another team.