A buyout is an agreement in which a player gives back part of their guaranteed salary in exchange for being released early, usually so they can join a contender after the trade deadline.
HoopSim has no buyouts. A player and their team cannot negotiate a reduced payout, so the only way to part with a player under contract is to trade them or to cut them, and a cut leaves every guaranteed year on your books as dead money. The nearest tools are the stretch provision, which spreads a cut's later years over more seasons during the offseason and preseason, and the fact that undecided option years leave nothing when a player is cut. Free agency stays open after the trade deadline, so a player another team releases can still be signed in season.
Rulebook: Dead money. Related: waive, dead money, trade deadline.