Cannot decrypt or backup files

Hi Everyone,

I am getting some failures in my backup software when trying to backup certain files. After some digging it turns out these files are encrypted, however when I try and clear this box:

I get these errors:

I am unfamiliar with encryption. I have taken ownership of the file and I do have permission, I can also delete and rename the files. Just not open or back them up. 

Can someone make a recommendation how I can unencrypt them or at least allow them to be backed up?

Thanks

Dave