If you subscribed to Online Orders from the Clover App Market, you can cancel your Online Orders subscription by simply uninstalling the Online Orders app from (all of) your Clover device(s).

You can also cancel from your computer  

STEP 1:  Go to Clover and log in.
Input your login credentials.
STEP 2:  Click on More Tools.
STEP 3:  Click on Installed Apps.
STEP 4:  Click on Online Order

STEP 5: Click on the 3 dots and click uninstall