Problems with I2C 2004 display

If you go to File -> Preferences in your Arduino IDE, right at the top, it will show you the location of your sketchbook folder.

As for uninstalling libraries, for this case at least, I would move any folder with the word "Liquid", "crystal" or "LCD" in it's name completely out of your libraries folder. From both library locations.

Then follow the directions I posted above.