How do I deActivate two readers so that I can activate two new readers if I no longer have the two I

I have activated six readers and I got rid of two of them. I'm buying two new readers and want to activate them in ADE. How do I do that so I don't get the too many activations problem. I had a live chat with "Akhtar" but he was no help at all. He finally suggested I just try to avtivate the new readers and If I had a problem, contact them again. I've been that route before and had no end of trouble so I'm not going to take him up on his suggestion. Can anyone help?