McNichols was cut during Saturday's roster trimming, Cam Inman of The Mercury News reports.
McNichols gained some steam when he received first-team reps earlier this preseason, but veteran Alfred Morris' outshined the 22-year-old down the stretch. Jerick McKinnon (knee) has been ruled out for the 2018 season, so McNichols could either be re-signed for depth or added to the 49ers' practice squad if he clears waivers. Matt Breida and Morris appear to be at the top of the adjusted running back depth chart.