Durant's business manager, Rich Kleiman, informed Warriors general manager Bob Myers of the decision in recent days.
Durant and Kleiman are together in New York, where they've been mulling Durant's free-agency options. So far, it has been a fairly clandestine process.
Durant is still considering a number of scenarios in free agency, including a return to Golden State, league sources tell ESPN. The New York Knicks, Brooklyn Nets and LA Clippers are also believed to be considerations, sources said.
Durant, 30, can sign a four-year, $164 million deal with another team, and remains eligible to sign a five-year, $221 million deal with the Warriors.
Durant, a two-time NBA Finals MVP with the Warriors, suffered a torn Achilles tendon in Game 5 of the Finals on June 10 and is expected to need the 2019-20 season to fully rehabilitate the injury.
Every team pursuing him is expected to still offer him a full max contract.