What are these metal things sticking out from my basement walls? Can they be removed? If so, how?
They look like the form clips where large forms were held in place to pour the walls. They can be handy as anchors if you add furring strips to drywall the walls instead of drilling for supports. They were just there for the pour and can be removed.
For form leftovers like this we usually hit them with the angle grinder and then go back and forth with pliers until it snaps at wall. I wouldn't just directly hammer these as you might be surprised at how big of a chunk of wall you take out with it.
They're left over from the forming system the contractor used. You may remove them by striking them sideways with a hammer or repeatedly bending them with any other tool. They're hardened steel and will snap off.