For x-mas I got a Nokia but I broke it so I had to buy a new one. My mom set it up with her account and now everyone can look at my pictures because of the OneDrive upload. How do I stop this? I'm afraid if I delete them on the computer they'll delete on my phone as well.
For future pictures, you can disable Auto Upload by going to Settings > applications > photos+camera, and near the bottom, there is the option for Auto upload. You can tap on that, and choose to not upload photos.
If you do do this you will have no back-up in case your phone gots lost, damaged, or stolen.
The other (more drastic) option would be to do a hard reset on the phone, and set it up with an account associated to you, but you will lose all photos, videos and purchased apps/games on the device - the purchased content is associated to the primary microsoft account for the phone.