Hello Zueuk, 

You do not need to deactivate your old to reuse the username. If you log into Channel 9 with a new Live ID and create a new 'temporary C9 username' you can send us that username and we can move your new Live ID onto your old account. From that point on you'll log in using your new Live ID and we'll recognize you as your old username. Email me directly(golnazal@microsoft.com) to let me know your old and new username.

 

Thanks,

Golnaz