Hello,
Thank you for contacting us and sorry for any inconvenience that might have been caused due to that.
Can you please confirm if you’re not able to find the Exclude Posts option on your Sitemap General settings? If so, please note that some options are only available when you enable the Advanced Mode in Rank Math. If you’re unable to find the Exclude Posts option in Sitemap settings, it is possible that you have chosen to use Easy Mode. Please try to switch to Advance mode from Rank Math > Dashboard.

That should reveal the Exclude Posts option in Rank Math > Sitemap > General and from there you can exclude any post or page from your sitemap.
Hope that helps and please don’t hesitate to let us know if you have any other questions.
Thank you.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.