The closest thing you can achieve is to create new Editor Features Profile. To do this, you need to click at top menu in Godot (where Scene/Projects/Debug are located) next Buttons: Editor -> Manage Editor Features... There you have to create new profile and then you can turn off features you don't want one by one. Once you do this, unchecked features will be hidden and if there are no items left in group, then group itself will be hidden too. Note that categories (CanvasItem and Node in your case) will stay anyway, no matter if they have items or not, but they will be empty.