What kind/model of tractor did you acquire??? Did you adjust the sway/check chains on the lower lift arms with the attachment lifted up in the air?? There should be a chain on each lift arm. These control the "sway" of an implement attached to the lift. Each brand of tractor usually has a slightly different arrangement in the way they adjust so I won't even begin to try and tell you how yours should adjust. My 790 has a "turnbuckle" style adjuster on the sawy chain on each lift arm, with a pin through it that locks it in place (to keep it from getting out of adjustment by itself).
To adjust it, park the tractor on a level spot and raise the implement. With the tractor off, and park brake set, swing the implement (by hand) back and forth and notice how much sway it has. This will tell you if you really need to adjust them. If there is a lot of sway in it, then place the implement in the "center" so it's directly in line with the tractor. Adjust the linkage adjusters to take up any slack in them. This *should* all but eliminate the sway. You need a little bit of sway in it, but not much, but it should keep the attachment or lift arms from hitting the tires.
As for removing the 3pt tiller, again find a level parking place and drop the attachment. Sometimes when you drop the implement, you will need to block it up with wood or bricks so it will be parked level. (This really helps during reattachment) Turn the tractor off and set the brake. Assuming here you have no quick attach or Pat's easy change setup, disengage the lift arms by removing the lynch pins. Swing the lift arms out to the sides. Sometimes you may have to readjust the sway chains/turnbuckles to give you some slack so the arms can swing out and clear the pins on the implement. Remove the top link. Disconnect the PTO shaft (if it uses one).
Start the tractor up and slowly drive away, being sure that the lift arms clear the attachment.
