Clear all the data of google app then
Go to play store > options> [![My 'Apps&games' >][1]][1] 
[1]: https://i.sstatic.net/3JG6Z.png
Go to 'installed'>Google app > uninstall 
Now don't do anything it will show to two options 'update' and 'open'
minimize and close play store.
then head to the settings > storage & USB > internal storage > Go to google app 
Now you should be able to disable it,