Sync local folder with USB-stick

Hello,
I have two folders named "School". One on my USB-stick, the other local on my Mac.
I made a rule for both folders to sync with the other. But it doesn't sync when I delete a file. How should I set up that if I delete a file in one of both folder, it automatically will be deleted in the other?
Thanks in advance for your reply!
I have two folders named "School". One on my USB-stick, the other local on my Mac.
I made a rule for both folders to sync with the other. But it doesn't sync when I delete a file. How should I set up that if I delete a file in one of both folder, it automatically will be deleted in the other?
Thanks in advance for your reply!