Is there a way, or an extension, in opencart 2.0.1.1 that will modify the Category module so it only displays the current top level category page's sub-categories.
For example, if I am on the "Laptops & Desktops" category page, the sidebar module would only list the sub-categories associated with "Laptops & Desktops" category, such as "Macs" and "PCs" with the main heading "Laptops & Desktops" (And not list or show any of the other top level categories).
Download the modules from the link below and set the modules which will show Show only subcategories on category page.
Show only subcategories on category page OpenCart 2.0 free module
Taking your requirement into consideration you should disable Category module and activate "Only Sub-Categories"