ReadyDriver Plus is a program that makes some modifications to the Bootloader and then makes the Windows start in Disable Driver Signature Enforcement mode.
— How to remove Ready Driver Plus?
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.
In most of the cases..., Revo will delete everything about the application, but if it doesn't do that, launch it again and use the Advanced Uninstaller. Look for Ready Driver Plus in the list and force uninstall it. Read more