From MLB.com:

Williams has apparently rejected the Yankees' offer of a non-roster invitation to camp and is not expected to report to the team's Legends Field facility. His agent, Scott Boras, informed The Associated Press of Williams' intentions.

"Other than the invite, there wasn't any information that led him to believe he would be a member of the team," Boras told The AP on Tuesday. "He's continuing to work out [and] will wait to see if their position changes." ...

"If he wanted to be here, he'd be here," Cashman said. "You'd have to be stupid not to interpret the answer. He's given us the answer."