Remove original image backups from Nextgen?

Is there any way to remove original image backups from Nextgen Gallery?
I have 5133 pics in my nextgen installation. Clearly, keeping the originals on the server, is taking up a vast amount of space. So I need a solution for this.

On the Nextgen Gallery tab “Other Settings”: “Backup the original images?”-radiobutton is checked “yes”. which means I have 5133 unlinked pics on my site(?): http://www.koegearkiverne.dk

I have found an old supportrequest submitted 2 years ago, but a solution doesn´t seem to have come up!? Plaese see http://wordpress.org/support/topic/plugin-nextgen-gallery-question-about-removing-original-image-backups?replies=4
Here, Alex Rabe agreed there is a good point.

Any help is much appreciated.
Best regards and thanks in advance,
Lars Kjær

https://wordpress.org/plugins/nextgen-gallery/