Problem with license quantity

Hi,

I have purchased 80 licenses of Symantec Endpoint Protection. I have syncronized my computers with Active Directory from Windows, and I installed 83 Endpoints on my network.

Passed some time, I removed 20 computers with my domain (it had SEP installed), but the SEP Manager say that have 83 used licenses.

How to make to update this number of 83 to 63 used licenses ?

Thanks!!