Legal Question in Technology Law in California

In most circumstances a gift immediately becomes the recipient's property. The giver has no more right to take it away than anyone else. But there are such things as conditional gifts, which the recipient is only entitled to keep while the conditions are met.

There may be other reasons why your friend would be entitled to take the computer back. Those reasons don't come up very often. Without more facts, I can't say whether any are present here.