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.
After that, try running Combofix to make sure that there are no leftover rogue registry keys or toolbars in your system.
If the installation is driver-related, you can go to Device Manager and manually remove the modem from that location. You will find it under Modem or Network section.