How can I protect a course I created independently from being taken by the community college I substitute for, when I am about to teach it there?
I'm going to come up with a different answer.
Sometimes I've taken over a course from someone else. They've offered me their slides, exercises, questions, etc.
Sometimes I've stopped teaching a class, and I've offered my successor my slides, exercises, questions, etc.
I haven't been able to use anyone else's material, and I'm pretty sure no one has used mine. It's not much use - unless it actually tells you what to say, when I write a slide, I have some idea what I was going to say. No one else does, and they can often fail to make much sense of it.
They can't steal your course, your course is in your head.
(My favorite example of this was when we were giving a talk to prospective students. I usually did this course for our department, but on one occasion, a colleague did it instead. The colleague took my slides, and figured that these were going to be slides that introduced the department. What could they possibly say? I was told later by someone else who was there that there was a slide with a picture of my cat. My colleague said &quot;And this slide has a picture of Jeremy's cat. I've no idea why.&quot;  [I'm sure that it was there for a good reason, or to make a point, but I completely forget what that point was.])