How’s your home screen? I asked that because it might be a part of another app you might have installed that hijacked your system. What are you do is you put the phone into safe mode by powering off the phone normally but holding down on the power off option on the screen to get the safe boot 

option. Then you go into settings and apps and uninstall it through there. Then you boot the phone up normally

Go into your settings and find the apps menu then disable YouTube and try uninstalling again.