How can I hide sub sub categories of a category in left sidebox?

[Ajeh]

Go to the Configuration ... Layout Settings ...

Categories - Always Open to Show SubCategories
Always Show Categories and SubCategories
0= off, just show Top Categories
1= on, Always show Categories and SubCategories when selected

Turn that OFF and when you select a Category from the sidebox it will not open to show the subcategories in that sidebox ...

[gjh42]

The admin switch will work for hiding all subcategories, but if you want to show subcats and hide sub-subcats, you need something else. Categories Dressing has settings that allow you to display any range of category levels desired (among many other things).