Hey Chuck, why don't you try factory resetting your device as it roll back your device to time when it was out of the box !!! You can follow steps below to do that
- Turn your device off by pressing power button.
- Next step is to press and hold the Volume Up, Power and Home buttons together until you see an Android lying on its back.
- Now use the volume keys to scroll down to Wipe Data/Factory Reset and use the Power button to confirm the same.
- Scroll down to Yes, Delete All User Data and hit Power to confirm.
- Now back on the first screen, use the volume button to scroll down to Wipe Cache Partition and select with power button.
- Once done hit the reboot system now option to restart your device.
All done !!! You have got yourself rid of all the stuff saved by your sister !!!