If the person you need to remove from the Canvas site was added by Penn's automated enrollment process, you will not be able to remove them from the site. Similarly, if the person you need to remove was originally added as part of a bulk upload that was processed by Wharton's Courseware Team, you will not be able to remove them from the site. Please contact the Courseware Team for help.
If the person you would like to remove from the site was originally added with the interface (using the +People button), you should be able to remove them with these instructions. If you still have difficulty, feel free to contact the Courseware Team.