Hey @Dror, welcome to the Seller Community!
I'd be happy to help answer these questions. Currently, you cannot delete the history on your account. We recomend refunding all of your test transactions transactions so the reporting matches up.
Using Square Point of Sale is free, but processing credit cards does have a fee associated with it. We have a great article on the Support Center, with a complete breakdown of Square's fees.
Please let me know if you have any other questions! I wish you the best of luck at your expo sale. 😀
