Hello! Thank you for reaching out! That is strange how the option is greyed out. If you mean closed captions then depending on where it's coming from it may not be able to be turned off. If you mean when hovering over menu items that option is in Accessibility go to Home > Menu > Settings > All Settings > General & Privacy > Accessibility > Voice Guide Settings and turn it off from there.
If this does not help I would recommend trying a factory reset on the TV. Please let us know if this helped.
