I am currently trying to delete my wizard, and I have a castle from a bundle in his inventory. I cleared everything from the house and attic, and then I tried to put it in the shared bank. However, it did not allow me to put the castle in the shared bank and it said my castle had no trade items.
Check to see if you have Beastmoon Planters. With one of my castles, that was the problem. If not, you might have something else that's no trade in your castle like a statue or something, and those can't be moved through your shared bank as they're not tradeable between characters. You will have to take those items out in order for you to put it in your bank.
