Want to stop one NORTON 360 on my PC

Hi 

I  bought two NORTON 360 (5 days ago) and accidentally I activated both on two PC. But later I came to know that one NORTON 360 can be used by 5 users. I like to know how can i stop my other NORTON 360 so that we can use it when first Norton 360 expires. 

Gratefull if any one can guide me.

 

Regards