Hello @tatami3lri
This actually depends on what you are trying to do. For example, disabling the sidebar globally can be done from the Customiser -> Post Type Name -> Sidebar/Layout, something like shown in these documents: https://creativethemes.com/blocksy/docs/post-types/single-posts/, https://creativethemes.com/blocksy/docs/post-types/pages/.
Alternatively, the sidebar can be disabled per page/post, using Blocksy’s page settings screen: https://creativethemes.com/blocksy/video-tutorials/customization/checking-out-blocksys-individual-post-page-settings/
Hope this helps!
Thanks.