Go to the MainWP > Extensions > Code Snippets > Saved Snippets page
Locate the Code Snippet that you want to remove from your child sites
Click the Load button
Once the Code Snippet loads, unselect child sites where you want to remove the snippet
Click the Save & Execute Snippet button.
This process will remove the snippet from all your site and re-add it only on sites that are still selected. This method is recommended in case you want to keep your snippet saved in the Save Snippets list so it can be used again in the future. If you want to remove the snippet from all child sites, you can un-check all sites and click the
Save & Execute Snippet button.