Amazon coupons....How the hell do you remove them??

[Ismisus]

I entered a coupon code (5 off 35). Then I had to buy another thing, which put my order over the 100. Obviously I wanted to enter the 10 off 100 coupon. But I don't know how I can remove the old code, so I can enter a new one. help.

PS. Sorry for posting this in "I wanna" thread, I don't think it goes there.