The following instructions are for Outlook for Windows, and describe the steps for changing the permissions of an Outlook calendar.
1.) Open Outlook.
2.) Choose the calendar view tab or icon. The calendar view icon is colored blue in the example image below.
3.) On the left side of your screen will be a list of Outlook calendars that you own, or share with others. To change a calendar’s permissions, Right-Click on the name of a calendar and choose Properties… from the menu, or click the Calendar Permissions icon near the top center of the Outlook Interface, while in the calendar viewing mode.
A Calendar Properties window will appear. There are a number of options within the Calendar Properties window. Users can be added or removed, and individual permissions set.
4.) Add a user, or edit an existing user, and set their permission level by choosing among the provided options. When you are finished, click the Apply button, then click the OK button.
Repeat the steps above for each calendar for which you would like to change permissions.