How do I uninstall the LINE app (third party app)?
Seems like 'Line' has been converted to a system app. You can convert it back to a user app and uninstall it if you have root permissions by using apps like App Uninstaller or System App Remover.

Otherwise you can disable it after uninstalling updates. "Disable" button can be found besides the "Force Stop" button under Settings &rarr; Apps &rarr; [offending app]

Else restore your phone (preferably from a Nandroid backup if you're rooted with a custom recovery). Even a factory reset might work.