He took over a program that had gone 0-9 the previous year, and reached the playoffs each of his five years as coach.
"What he's done for the school and community cannot be measured," Guzzo said.
Uzelac said there was a conflict with administration over his contract, which expires at the end of June, so he decided to step down. He declined to elaborate, preferring to focus on all the good memories he made at St. Joseph.
"(St. Joseph) is very special to me," Uzelac said. "Our football players, I love them dearly. I know we beat a lot of teams we weren't supposed to beat. The community was super great, they really were. The parents were great."
In a news release announcing his resignation, school administrators were complementary.
"Elliot's contribution to our community went far beyond the wins on the football field," superintendent Al Skibbe said. "The excitement and enthusiasm that was created infused and lifted the entire district. Elliot's commitment to excellence was evident in everything he did. He was a role model on and off the field."
Board president Amy Porritt-Peirce added: "His own actions proved that hard work and dedication to a goal could bring success to any endeavor. He will be greatly missed by the entire St. Joseph community."
The search for Uzelac's replacement should be completed within the next week, and will likely be an internal candidate, Guzzo said.
"One credit to Elliot is he had a great staff," Guzzo said. "Right now our best bet is to have someone from within take it over, and we feel like we've got several good candidates."
Before coming to St. Joseph, Uzelac was an assistant coach at Bowling Green, Michigan, Indiana, Ohio State, Colorado, Kentucky, Maryland, Minnesota, and the NFL's Cleveland Browns. He was also the head coach at Western Michigan from 1975-1981 and at Navy from 1987-1989.
Uzelac said he'll "wait and see" whether he will coach again.