In case you installed a misbehaving app via Cydia, manually removed it using iFile or Filza, but can’t seem to remove it from the “Installed” list/section, here’s what you can do:
1. Using your preferred file manager — in my case, Filza — navigate to “/var/lib/dpkg/status”
2. View the app with “Text Editor”
3. Click anywhere inside the text, and click on “Edit” on the top-right
4. Search for “My3G” and delete the whole section (i.e. com.sull…)
5. Save and reboot your phone (not really needed, but it “feels” cleaner)
That’s it! Enjoy your jailbroken phone once again.