I broke a key into one of those uhaul security locks .The one that round. Any ideas on how I can get it open?

You can try a pair of tweezers on it.

Take sticky tape to it, press and maybe it will adhere long enough to pull it out?

It would be easier just to call the lock smith, who knows what they charge these days?

Well here is all I can think of....

Superglue

you don't have any choice. Uhaul will charge you or you can charge yourself and get it out of the way

call a lock smith