Right now I don't have Internet and I have Super Mario Maker on Wii U. I made a variety of levels, ready to upload them when I have Internet again. I found out that if levels are so unpopular and people barely play them, Nintendo deletes them from Course World. I'm fearing that if I upload some of my courses, some might be deleted. I want to know if Nintendo deletes a course from course world if I can still play it on MY COURSES, and possibly edited it and make it better so I can upload it again? Please let me know.
The "My Courses" under CourseBot is your "Offline Storage" for the levels you've made. Even though you have limited space on CourseBot, each one of those spots are for your levels only and will not be affected if a level is deleted from the online side of things.
If a level is deleted from the server, then your "Uploaded Courses" from Course World will be the only thing affected. CourseBot will update as well to remove the "uploaded" mark, but that course will still be on your system. (Assuming you had not manually deleted it sometime after uploading it.)
In short yes you can still play it, but only if you have it on your Wii U still. They cannot delete it from your hard drive on the Wii U. There for you would be able to edit again and upload it again if you pleased. This will also go for any course you downloaded from online on to your Wii U.