I don't know this phone, and mine has no such feature, so I doubt I can help with the setting itself. Though it does seem strange to have a "setting" that cannot be changed: what's the point of putting something in the advanced settings if you can't interact with it? So are you certain it's not changeable, e.g. you've tried tapping the text to see whether it opens up further options?
A work-around would be to buy a case that surrounds the power button so that it's harder to press the button in the pocket. But it seems just too weird if there's no way to disable it.
(I'd suggest checking the developer options, which is normally a hidden menu, but this isn't the sort of thing that you'd put in there. If you want to look, find the software version information in your phone's settings and tap repeatedly on the "build number". That will unlock the developer options menu - a stupid way of doing things, but that's Google).