How can I delete transaction History off my IPhone?

Well, all of the transactions on your cards and bank accounts are a misuse of your privacy because your financial institutions share them with merchants and government auditors, but your transactions on your phone are not, because it is YOUR phone with YOUR password locking it, so no one else can ever see them unless you let them.

You can’t. It is part of your permanent record, just like all the charges on your credit card and all of the transactions in your bank account.