Shares and links: go to Settings → Access Sharing, pick the property, and select Manage Access. Under Who Has Access you'll see each person and link you've shared and what they can see. Select an entry to expand it, then select Revoke Access.
Realtors and contractors: open the property menu (the gear icon next to your property's name) and choose Grant Access. Under Realtors and contractors with access, select Remove next to them and confirm with Remove access.
Members of your home: select the people icon at the top of your dashboard. Select the trash icon next to a member and confirm with Remove, or Cancel an invitation that hasn't been accepted yet.
Access ends right away. You can always share again later.