Hello there, @707mrk ...
I'm a bit confused what you mean by "default" pages, modules, navigation apps, assignments, etc. Would you be able to provide an example or two (maybe including a screenshot or two being careful not to show any student data) of exactly what you are seeing on your screen and what you are deleting? My suspicion is that this might be something you could work with your school's Canvas admin (or someone from your school's Online Learning / eLearning / Distance Education) team on, but it might be good to see an example here, too, since we do not have access to your school's Canvas environment or any of your Canvas courses.
Thanks, and looking forward to hearing back from you soon. Take care...be well.