To roll back a previous upload, click on Multi Site Upload, on the next screen select the Upload History tab, this will display a list of historical uploads, click the complete or in error button on the upload you wish to roll back this will open it up. Next select the "Rollback" button. The upload has now be removed from your activity data. 

Uploads can also be restored by following the same directions expanding an upload job from the list of historical uploads on the Multi-Activity Upload screen and selecting the "Restore this upload" button.