Smith, who started 32 of 33 games last season, averaged 9.7 points per game and was second on the team in assists and 3-pointers.
"Deville informed me that he has decided to leave the program," UNLV coach Dave Rice said.
Smith's departure leaves UNLV without each of its top five scorers from 2013-14.
Rice has lost his third transfer this offseason, with leading scorer Bryce Dejean-Jones leaving for Iowa State for his senior season and forward Demetris Morant moving to Florida Gulf Coast after one season with the Rebels. Juniors Khem Birch and Roscoe Smith declared early for the NBA draft, running UNLV's losses to seven players, including graduating seniors Kevin Olekaibe and Carlos Lopez-Sosa.
The Associated Press contributed to this report.