The team used the vacant roster spot to sign offensive lineman Senio Kelemete to a one-year deal.
Skule suffered a torn ACL during practice on Monday, June 7. Safety Tarvarius Moore was injured during the same session, suffering a torn Achilles. Last week, he underwent successful surgery to repair the damage.
San Francisco made Skule a sixth-round draft pick out of Vanderbilt in 2019. He has appeared in 31 games with 12 starts in his two seasons. The offensive lineman was on track to become the team's top backup to tackles Trent Williams and Mike McGlinchey.
San Francisco will also begin the 2021 season without running back Jeff Wilson Jr., who suffered a torn meniscus in May. He is not expected to return until about mid-season, perhaps as late as November. The running back will likely begin the season on the physically-unable-to-perform (PUP) list.