Good morning, @pyyu Welcome to the Canvas Community. Thank you for posting your question. I have some great news for you! I'm not sure if you regularly follow the Canvas Release Notes that are published each month, but in the https://community.canvaslms.com/docs/DOC-18528-canvas-release-notes-2020-03-21 document, the ability to hide/remove the "Course Summary" section in your course Syllabus is coming! In fact, if you want, you can see how this will work right now by logging in to your school's "beta" environment. How do I access the Canvas beta environment as an instructor? So, all of us have to wait just a couple more week (March 21, 2020), and then we'll be able to toggle the "Course Summary" on/off as needed.
I hope this helps...please let us know if you have any other questions about this...thanks!