As asked previously - did you purchase direct from Magix? If not you probably need to approach whoever you got your software from and ask them to deactivate it.
You may not lend, lease or sublicense the MAGIX product temporarily or permanently. However, you may transfer the license for use of the MAGIX product as a whole to a third party, provided that you completely remove all installations from your computer and do not retain any backup copies. You must then release all MAGIX product license slots in your user account and allow the third party to register the MAGIX product in their user account. If the aforementioned conditions are not fulfilled, any transfer of the license of a MAGIX product requires the express consent of MAGIX."
I did that and gave my VMS 15 pl to my grandson and he could not register it. So I ask Magix support to delete that product from my account and when they did that ( the next day) my grandson could register.
BTW. An employee at Magix deleted all my registered products( by accident?????) so I had to register from start all my installed products on laptop and desktop.