Remove sidebar from only single blog page

How can I remove the sidebar from the single blog page? I have a custom post type which I want to keep the blog on so I carnt use is_single() as it removes it from the custom post type single page.

this is more a general WordPress question and not so much Roots related and it’s better you ask this kind of stuff on WordPress forum or Stack Overflow… but to point you in the right direction:

In the Roots sidebar.php template file you can control when sidebar’s are displayed with conditional statements, such as:

if ( is_singular('custom_post_type') ) {
   dynamic_sidebar('name_of_sidebar');
}

Or you could wrap the above code around the <aside></aside> in a custom template and use less/sass to make your <main> full-width or not by targeting off of body classes (you should have a body class for your custom post type).

to control when sidebars are displayed you should use roots_display_sidebar() function in config.php: https://github.com/roots/roots/blob/master/lib/config.php#L44. just enter the conditionals in the function. this will also take care of the width of the main element.