This is per Matt Maiocco. I just copied his tweets.
Ex-49ers RT Anthony Davis cited what's best for his body and mental health for stepping away. He missed time last season with a concussion.
Matt Maiocco ✔ @MaioccoCSN
#49ers GM Trent Baalke says organization thanks Anthony Davis for his contributions ďand wishes him the best as he moves on from the game."
I also saw that Davis said he is taking a year or two off from the NFL. Wow, what an off-season we've had. The hits just keep on coming.