I have a fresh installation of OpenERP 7 with Accounting module installed. During installation, I have selected Custom Chart of Accounts and put the tax rate at 7%. When I view Accounting>Chart of Taxes, I see there are Tax Received Rate S (15%), Tax Received Rate R (5%), Tax Received Rate X (Exempt), Tax Received Rate O (Out of scope), and Tax Paid Rate S, R, X, O as well. I would like to remove some of these categories such that I have only "Tax Received at default rate" and "Tax Received Rate X". What is the best way of doing this?