Sale Tax Schedule

SOLVED

Hello,

Two questions.. First how do I disable/remove a Sale TAX Schedule that is no longer needed. If it can be removed how will that affect history?? 

Next... I have a customer with a tax schedule of WA2717 in its customer record but when I create a new SO and use them as the customer the Tax Schedule that is populated is WAPIEP it is not the same as it the customer record??

Any help would be greatly appreciated