Hit it with a hammer, superglue hardens brittle so with enough solid hits it'll shatter out slowly, but can take time. If they stick milliput in though it's easier to just go get an angle grinder.
Using acetone is much easier. Superglue will dissolve in acetone. May take a few minutes and a few reapplications for the chemical reaction to do its thing. A lot of locksmiths use acetone on locks (home entry locks, padlocks, and bike locks) that vandals decide to put superglue in. Using a light grease in your lock will help prevent superglue from bonding...all you want is a coating that will last longer than a spray oil.