Are you a student or a teacher? I ask because you reference the teacher and designer rolls, which would not normally be options for students. Either way, this may be something that you will need to talk to your tech department about, or even whomever manages Canvas for your institution. Canvas course enrollment might be tied to another service and automatically done. For example, we have an SIS system that is synced to Canvas. When someone is added/removed from a class, the system will handle enrollment (usually have to wait until the next day). If your institution uses a system like this and you are still enrolled in the course within that system, any attempt to unenroll in Canvas would be overridden. Since this forum is primarily comprised of community members, we would not have access to your institution's system or Canvas instance to look closer. Your tech department or Canvas administrator would be better equipped to handle this issue. Whether you are a student or teacher might impact who would be the person to reach out to (general tech support or a specific person). Best I can suggest is having them look into why it won't let you unenroll. Maybe someone else with more experience on that side might have another solution (I am more on the instructor side of the system).
Now, if they cannot figure out what is going on, that would mean they should talk with their Canvas CMS or put in a support ticket for Canvas techs to look into. But that would be better after seeing if someone at your institution might have the ability to look into is going on. I know this is not as time-saving as you would desire, but this likely could be in place to help mitigate issues that arise from someone accidentally unenrolling.
