Wow what a nightmare for newbies. I could not figure out how to access the recommended bat file (above) because the battling Start8 and Start10 "Start" buttons flashing back and forth blocked my access to Windows. So, I parked my Lenovo E431 on a shelf until I could figure out a factory reboot.
So today I revisited this thread, fired the Lenovo back up, and received a Start10 update notification. Installing that allowed me to click on the Start icon, which turned out to be Start8, not Start10. I clicked on Configure Start8 but the closest option to "Uninstall" was to deactivate.
After deactivation and the resulting nag screen (with no option to Uninstall), Start8 allowed me to the Control Panel and uninstall both Start8 and Start10, but when it rebooted Start10 was still active. Despite declining to uninstall, it seems to be behaving itself for now.
My understanding of tech is low, but shouldn't installing Start10 automatically uninstall Start8?
And it would be nice if your Configure menu had an option to Uninstall. I was sure it would be there, but I could not find it.