Barrel off center

Recently bought this used PSA AR for pretty cheap. When trying to zero it, I realized the barrel is pretty far off center in the handguard. As you can see, the windage on my rear sight is cranked pretty much all the way to the right. I also bottomed out the front sight post, and it is still shooting low. At first I thought it might be the handguard, but my red dot also has windage and elevation very far off center. How can I fix this?