which can be located in your Microsoft Office directory tells you basically how you can sell or give away your licensed copy of Office.

If it was an upgrade from a previous version that previous version must accompany all the software.

What will be necessary in your case (since you want it in your name but it is already installed) is for you to get all the necessary installation disks from your friend. Next you uninstall it from the computer. When you re-install it you MUST choose the telephone activation method and simply explain the situation. You then register it in your name also.

Relatively painless.