How to: Delete PowerPivot Gallery
Deleting a PowerPivot Gallery also deletes all of its items, including the data refresh history for PowerPivot workbooks that are configured for scheduled data refresh.
This topic provides instructions on how to delete a SharePoint library. For instructions on how to delete individual documents in the library, see How to: Use PowerPivot Gallery.
You must be a site owner to delete a library.
Delete PowerPivot Gallery
Click Site Actions.
Click Site Settings.
Under Site Administration, click Sites libraries and lists.
Click Customize "PowerPivot Gallery".
Under Permissions and Management, click Delete this library.