Remove sidebar from posts

the template responsible for single posts is single.php http://codex.ww.wp.xz.cn/Template_Hierarchy – if that template is not yet in your child theme’s folder, make a copy of it from the parent theme and add it into the child theme.

then try to edit that single.php template and remove the sidebar code.

if the issue persists, please post in your theme’s forum at https://ww.wp.xz.cn/support/theme/catch-box/