Can a bank close a customer's checking account without notice if the bank beleives the customer is Kiting?

Yes. Although, we do not mention the word "kiting" in our letter that we send them, we state we have noticed "suspicious or unusual activity".

Would anyone be willing to share a letter that says we are closing you immediately? We are in the midst of trying to put together a letter for an account we are closing due to fraudulent activity.

What does your terms and conditions say? Our says we can close the account at any time upon reasonable notice to the customer and send the account balance either personally or by mail.

Due to recent activity on the above referenced checking account, XZY Bank has decided to to close the account.

I would not even go that far. Accusing someone of acting suspicious is far farther than a bank wants to go. Just tell them that you are terminating the relationship based on the term of your depositor's agreement and leave it at that. Otherwise, the bank may get accused and it may lead to all kinds of future headaches.