Lilley's departure from the Rhinos, who have struggled financially in recent years, comes amid speculation about their future. A club press conference is scheduled for Wednesday.
Brandt was hired by the Hounds partway through the 2016 season after a successful career at Division III power Messiah and Navy. In his first full season, Pittsburgh improved from 25 points in 2016 to 36 points in 2017.
“We are highly disappointed with this news, but understand the necessity to comply with the league’s decision,” Riverhounds owner Tuffy Shallenberger said. “Dave has been nothing shy of first class since joining the organization. We are incredibly grateful for his contributions to the Riverhounds and has left the team in a significantly better position than when he arrived.”