By hitting F12 you open the browser’s element inspector, for example, Firebug. Then you will edit the div line who’s id is “vc-preloader”. This will temporarily remove the loading layer and allow you to edit the page but it is not a permanent solution. You will need to take these steps every time you edit a page.
Here’s an example:
https://s14.postimg.org/oi6ol8n6p/Untitled_1.jpg
