Deleting a Custom Media Type

You cannot delete a Custom Media Type that is referenced in a content rule

From the Policy Center Home page, click Custom Media Types. The Manage Custom Media Types page appears listing the existing Custom Media Types.
Select the Custom Media Type you wish to delete.
Ensure that no content rules are using this Custom Media Type (). If it is being used by any content rules (), you must edit the content rule to remove the reference to the Custom Media Type in the Which Media Types clause before you can delete the Custom Media Type. For information on editing a content rule, see Working with content rules.
Click Delete.

When you have finished modifying your content security policy you must apply the configuration for any changes to take effect. If the Gateways are configured as a group, any group changes should be applied to each Gateway.