Welcome to the Zoom Community, @CCC-3/.
By "removed" do you mean they are not a Co-Host when they attend a future meeting? Unfortunately, this is the way Zoom is designed to work. The designation of Co-Host manually assigned during a meeting is not persistent to future meetings.
This Zoom Support article on the roles during a meeting might be helpful to you:
https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0064033
If your intended Co-Hosts are Licensed and their user account is in the same organizational account as yours, you might consider using the Scheduling Privilege to allow them to start meetings in your absence, since Scheduling Privilege also allows that person to be Co-Host on entry into the meeting, in my experience (though I can't find any documentation that states this).