Are you a Creative Cloud subscriber?
If yes, log-in to your online account and deactivate unwanted devices. Your license allows you to install on multiple devices but only 2 may be activated at the same time.
If you're not a Creative Cloud subscriber, you must manually deactivate from the device via your installed software's HELP menu. If you require an activation count reset, contact Adobe support directly and request one.
CONTACT ADOBE SUPPORT:
Online Chat: https://helpx.adobe.com/contact.html?rghtup=autoOpen
Phone M-F, during normal business hours: https://helpx.adobe.com/contact/phone.html
Hope that helps.
Nancy O'Shea, Product User & Community Expert
Alt-Web Design & Publishing ~ Web : Print : Graphics : Media