Cannot uninstall SecureLine VPN (and never agreed to install it)

I can’t uninstall SecureLine VPN (for iOS). When I go to About → Uninstall, I get the attached error. When I quit and then delete the app, it says it’s still running. It’s really frustrating because I never agreed to download it and it pops up multiple times a day.

See: https://forum.avast.com/index.php?topic=166545.0