Hi,
You can edit the joomla menu "sar store" via the joomla menu manager. There, click on the "HikaShop options" link to access the HikaShop options. Then, for the option "Show sub categories", you should set it to "no child" and finally save. That should remove the sub categories from that page.
For a listing of main categories on the side, I would recommend to create a new module via the HikaShop menu "Display->Content modules". Select the type of content as categories and select the menu "sar store" for the menu option. Check that the synchronize content option is turned off, that the parent category option is your main product category and that it is displaying only direct sub-elements. Set a title and click on apply. Then, click on the "joomla module options" in order to publish the module to a valid position of your template and save.
You should now have a listing of your main categories on the side.
