I agree that pulling would be safest. If you do that, it would be good to get the chain wrapped and choked real well on the posts. If the structure is pulled enough to make it unstable when the chain slips off it will increase the danger if you have to monkey with hundreds of pounds of things that want to fall on you.
You said you want to re-use the roofing. You'll need to decide if it would be an approach you want to try without some assistance, but based on the pictures Here's what I'd do. Use the loader to lift the low point of the roof and get a post back in there. Then start removing roof panels from the end farthest from the building. It looks like the metal is only about 8' off the ground. The first piece of tin could probably be removed using a stepladder placed on the outside. Next piece would put the stepladder under the framing, so it would be important to keep checking the stability of the framing as you go. Without the rigidity the tin adds, the framing may want to twist, rack and come down.