In cutting their roster to 15 players, the Knicks did not make a sentimental move.Instead of keeping Patrick Ewing Jr., the Knicks waived him and opted to keep Shawne Williams as the team’s 15th man. Ewing Jr. reportedly had a $100,000 guarantee. It marks the second time in three years that the franchise cut the son of their legendary former center, now an assistant with the Orlando Magic. Knicks president Donnie Walsh initially drafted Williams to Indiana with the No. 17 pick in the 2006 NBA Draft out of Memphis. Dan Barto of IMG Academies in Bradenton, Fla., worked with Williams, as well as Lakers rookie Derrick Caracter, this summer and believes he can help the Knicks. “He worked very hard not only to get ready for camp but also to improve his game and techniques,” Barto said of Williams. “He has a tremendous understanding of the game and has the ability to be a perfect stretch shooter in [Mike] Dantoni’s fun and gun style of play.” FREE THROWS The Knicks exercised the fourth-year options on Danilo Gallinari and Anthony Randolph and the third-year option on Toney Douglas. All three players have been mentioned as potential chips in a trade for Carmelo Anthony.