How to bulk delete galleries (and images with them)?

From a customer:

In an effort to reduce the size of the site, John and I discussed getting rid of most of the galleries currently taking up a lot of space on the site. However, there are roughly 500 galleries we are looking at getting rid of, but unfortunately the plugin (FLAGallery) does not have a way to bulk delete.

What would be the easiest way to handle this?

Basically, we want to delete specific galleries and all associated images. I know you utilize WP Media to store the images… we’d like those to be removed, as well.

Thanks!