Thank you so much for using our theme Grip.
If you want to make the side without sidebar, you can make the site without sidebar via
Appearance > Customize > Gist Theme Options > Blog Section Options > Select Prefered Sidebar from this Options. Now, if you select no sidebar, the whole site will without the sidebar.
But if you want to make the full width only on single pages, you need to purchase the premium version. The premium theme has this option to set the sidebar for individual pages.
Please let us know if you have any queries.
P.S. Currently, we are offering 25% discount as well. You can check and purchase it.