McKenzie was given the chance to finish out the season but chose against it, NFL Network's Ian Rapoport and Tom Pelissero report.
It was reported Sunday by Jason La Canfora of CBS Sports that McKenzie wasn't expected to return as the Raiders overhaul their front office this offseason.
McKenzie served as the Raiders' GM for seven seasons. During that time, Oakland compiled a 39-70 record.
However, he did lead a two-year turnaround. Oakland was one of the worst teams in the league in 2014 before challenging for the top spot in the AFC in 2016. He was named Executive of the Year after the 2016 season.
Jon Gruden was hired as the team's head coach this offseason and inked a reported 10-year, $100-million contract. He's also believed to have roster control.
In the time since, the Raiders have traded away Khalil Mack and Amari Cooper, both of whom are leading playoff charges for their respective teams. At 3-10, Oakland shares the worst record in the league and is challenging for the No. 1 pick in the 2019 draft.