The steps you need to take to transfer the software - and a licence - from one tutor machine to another vary depending on the version of AB Tutor Control you wish to move, and on the method you used to activate the software.
If you are not sure which version of AB Tutor Control you are running on the machine from which you want to remove the software, launch AB Tutor Control on that machine and select Help, About AB Tutor Control.
We would always recommend that you check the installations that are registered in your account before you attempt to move your installations.
If you installed version 3.x then upgraded those licences to version 4, follow the instructions for 'Version 4 - automatically activated via online registration.'