Once you have a media element in your "Media" tab, you can drag and drop it anywhere within your PageDip and reuse it in multiple places.

When you want to delete a media element, first decide if you want to delete all instances of the entire media item or just the media item within that specific PageDip. In other words you can delete a media item within the body of a specific page but still have it remain in your "media" tab to be used elsewhere.

To delete a media item within the content of your PageDip, simply highlight the media item and press delete.

If you want to delete the media item within the "media" tab, and have it permanently removed, go into the "media" tab, select that element and click on the trash icon or the delete file within the setting tab of that media item. A popup asks you to confirm this decision.