Delete CDR files from system

I have (manually) downloaded the CDR files starting from a certain date, and no longer want to leave those files on the SBC. I went into the system using Filezilla, and have found that I cannot delete any files because I do not have the appropriate permissions.

You can ssh to the ProSBC, then use sudo to delete the files.
e.g.:
sudo rm -f gateway_2020-12-06.log.gz