Greetings, Keeshagurl.
I see that you've found someone else's Apple ID installed on your iPhone 4s. I'm happy to help.
Turn off Find My iPhone Activation Lock
If the device is linked to a previous owner's account and they're close by, ask them to enter their Apple ID and password on the Activation Lock screen and remove the device from their account.
If you see the passcode screen and the device isn't erased, ask the previous owner to unlock the device and go to Settings > General > Reset > Erase All Content and Settings. They'll need to enter their Apple ID and password.
If the previous owner isn't present, contact them and ask them to follow these steps:
- Sign in to iCloud.com with their Apple ID.
- Go to Find My iPhone.
- Click All Devices at the top of the screen.
- Select the device that you want to remove from iCloud.
- If necessary, click Erase [device].
- Click Remove from Account.
After the previous owner removes the device from their account, turn off the device and then turn it back on to begin the setup process.
Take care!