Deselect All , keep clicking other object

sometimes when I select an object and want to opt out of it , but it just keep clicking other objects and it keep clicking like that.

I tried Select All. But it didn’t really work out easily and it need a couple try of keep clicking.

Is there a shortcut to Really unselect all Completely?

Ctrl + T (Edit > Select None)

Ctrl+T will deselect selected entities. If you have groups or components open for editing you can back out with Esc.

Here I’ve used Ctrl+T to select the geometry and Escape twice to back out to the model context.

I did used it.

but it just a little bugging me that it not go back to the Normal environment (like with all the color for objects, sometimes, it’s only have color the object I clicking and other stuff is greyish).

That’s because Ctrl+T delselects which is what you asked for in your original post. To back out of the edit mode use Esc as I showed.

Clicking the title in Outliner will Deselect All.