You can turn the grid on and off there just isn’t a shortcut for it. The most direct way is the Filter menu on the view window where you want to turn it off. If you click on the Filter menu one of the choices is Grid enable or disable there.
If you want to add it to your HUD you need to go to the Filter menu’s actual home in the Edit/Configure menu of the view window, the Viewport info will appear in the Attribute Manager on the right, in there go to the Filter tab you will see the same choices as were in the Filter menu, this deeper menu is harder to get to than the Filter menu but it does have the nice feature that you can drag any of the values there into the view window, click on the word Grid and drag it into the view window. The button this makes will give you control over the grid. Most values in the Attribute Manager can be added to the Hud in this way.