Cleaning up coredumpctl list

I'm looking for a way to remove any trace of old coredumps in coredumpctl list. At the moment it lists coredumps beginning at 2014-12-14 - I've updated software so often between then and now that I doubt those old coredumps are going to help me debug any problems now. Unfortunately removing the files from /var/lib/systemd/coredump only made the asterisk in the "PRESENT" column of coredumpctls output disappear. I couldn't find any way to remove all information about coredumps in the manpages or in the help output of coredumpctl.