If you are a regular user, you might need to log-in using an Administrator username to be able to remove it. However, you can use an alternative way. 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 AdwCleaner to make sure that there are no registry keys or toolbars left in your system.
In AdwCleaner, make sure to browse to its tabs and deselect the software you want to be removed. If you check it, it will be kept on your computer.