The Share Control is the interface that lets you manage the share settings of all of your information in Keep&Share, including Calendars, Documents, Photo Albums, and more. Each Calendar, Document, etc. in your account has its own individual Share Control located in the pop-up ”Share” dialog - this gives you maximum control over your shared and private Keep&Share content.
If you have shared something in your account with someone and then you no longer want that item shared with them then you will need to go back to the Share Control and remove that person. Follow the steps in the image below: