The Delegate Access feature in Outlook 2016/2013 version offers a way for you to create a delegate for allowing someone else to manage and read only your meeting requests and responses, without having the appropriate permissions to access your inbox emails. To add a delegate, open start page of Outlook application, click Account > Delegate Access, and follow the on-screen instructions to complete the process. It is helpful for another person to respond your communications officially, but for some reason you might notice that Delegate Access option is missing and unavailable inside and here is the method to restore it.
How to fix Delegate Access Option Is Missing or not available in Outlook 2016/2013
* Press Win + R from your keyboard, type regedit in Run dialog box and hit Enter to open Registry Editor.
* Navigate to the location below in the left pane:
* Right click Microsoft key, and select New > Key, set the name of newly created key to Office. Right click Office key to create a new sub-key named 16.0 while you are using Office 2013 version, or 15.0 for Office 2013, or 14.0 for Office 2010. Then repeat the sae way to create sub-key named Outlook > the sub-key DisabledCmdBarItemsList.
* Now you should get the full location:
* Highlight DisabledCmdBarItemsList key and go to its right side pane. Right click any empty area, select New > String Value, set its name to TCID1, and change its Value data to 20103, and click OK button.
* Finally restart the system to apply all changes.