You can manage your store's design templates (skins) using the Layout page (Look & Feel > Layout) of the store Admin area.
If you visit this page, you will see that its upper part shows the design template installed and active in the store currently.
You can use the "Customize storefront" button to access the storefront customization settings.
For some skins, you may also be able to edit custom options:
If you wish, you can switch to using a different skin.
You can see the list of all available skins in the "Choose a new template" section of the page. A green frame highlights the skin active currently in your store. To switch to a different skin, select the skin you require in the "Choose a new template" section (by clicking on the skin icon) and click the Submit button.
You can purchase and download more skins from the X-Cart App Store. More info on this is available in the section Installing Skins from X-Cart App Store.
You can disable or remove a previously installed skin by deactivating or uninstalling the respective add-on via the My Apps section.