The jPC utilizes a udiskie user service to automount USB drives when they are plugged into the jPC. Each recognized partition will be mounted at /media/{user}/{partition_label}.
To disable this service, run systemctl –user disable jpc-automount. After rebooting, it will not longer start and USB removable drives will no longer be automounted. To stop the service immediately, without rebooting, run systemctl –user stop jpc-automount.