Demo images free to use?

Hi,

Are the images that come with the ColorMag demo site free to use? I’m not using them in any of my posts or pages on my site, but since I haven’t deleted them from my WordPress media library, they show up in my xml sitemap’s image sitemap xml. I just wanted to know if I need to delete those images from my media library to avoid any possible copyrights issues that Google crawlers might find with me leaving the images in my media library and penalize my site for using the copyrighted images (if they are copyrighted images). Even if they are free to use, would you recommend deleting them from my media library if I am not using them or could there be any harm in leaving those images in the media library (and hence them appearing in my sitemap/images sitemap xml) SEO-wise or otherwise?