Try using Revo Uninstaller. Even if it can't uninstall the application normally, it will force it to uninstall by wiping out all traces of its presence from the system.
Run Revo again after uninstallation and check it X-Proxy application is still present, then repeat the same process if you find it in the list.
After that, try running AdwCleaner to make sure that there are no leftover rogue registry keys or toolbars in your system.