To enable or disable mobile view, first click on the gear icon and then click on website settings. Then select or de-select "MobileEnabled" checkbox.
If you want to enable mobile view so that you can preview your website on a mobile device and with a desktop view, follow these steps.
When the "MobileEnabled" checkbox is de-selected, the mobile icon on the top dashboard menu is inactive and you cannot access the Mobile Studio. This means that your website, when opened from a mobile device, will look exactly the same as on a desktop.
Keep in mind that you MUST have a domain associated with the site. This can be your main domain name or even a subdomain (free from Exai).