The most common way to handle this is to create a “full-width” page template in your theme. This will be a near duplicate of your page.php file (if we are talking about WP Pages, not posts or a custom post type) without calling in the sidebar.
Looking at the structure of your page.php file, locate the block that contains <?php get_sidebar(); ?> and remove it in your full width template file. Depending on the specifics of your theme, you may also need to remove the DIV or SECTION wrapper code if it is not fully contained within the sidebar.php file.