You can use Change Sharing Permissions to view the people you've shared your calendar with and the permissions they have. You can also use Change Sharing Permissions to stop sharing your calendar.

How do I share My Calendar?

In Outlook Web App, click  Calendar in the Navigation Pane. Click Share on the Calendar toolbar. Click Share this Calendar type the persons name in the to: box Click Send.

How change the calendar sharing permissions?

In Outlook Web App, click  Calendar in the Navigation Pane. Click Share on the Calendar toolbar. Click Change Sharing Permissions  Click the name of the person whose permissions you want to change. Click Edit and select the permissions you want. Click Save when finished.

How do I stop sharing a calendar?

If you want to stop sharing your calendar with someone: In Outlook Web App, click  Calendar in the Navigation Pane. Click Share on the Calendar toolbar. Click Change Sharing Permissions and then, in the Calendar dialog box, select the name of the calendar that you want to stop sharing. Click the name of the person you want to stop sharing your calendar with to select it, and then click Delete. Click Yes to confirm that you want to delete that person from the list, or click No to cancel.