Avast Premier

Hello, I recently installed a new HD into my sons PC. However, his old HD is dead in the water. I read somewhere in order to use the Avast Premier on another PC, he would need to uninstall it on the old PC and deactivate it. Well the issue is, I can’t uninstall it because I can’t access the drive. What do I do?

Just install it on the new system/HD.