My friend asked me to sort out his Windows 7. When I got his computer home I realized that no isp was loaded. My friend is on BT and so am I. I decided to enter my email address (user name) and my password to get on the Internet. I downloaded Windows 10 (free copy) and sorted out a few programs etc.
Please tell me how to revert the computer to my friends user name and BT password without upsetting my configuration. Many thanks