Once a feature is on the map, you can remove attachments by taking the following steps:
If the location you tapped has multiple features with pop-ups, you'll see a pivot of those features (as shown in the previous screen shot). You can switch between the pop-ups by swiping from panel to panel inside the features window.
The Edit pivot displays on the attributes panel.
View a thumbnail of the attachment
Tap the attachment to see a thumbnail.
View a preview of the attachment
Tap the thumbnail to see a preview of the attachment.
Save the attachment to your phone
When viewing the preview of an attachment, expand the app bar and select save to phone. To find it on your device, go to the Pictures app, select albums, and open the Saved Pictures album.