Depends if they're on a LAN or not.
If its on a LAN all you have to do is know the netbios name of that computer, fire up compmgmt.msc and then right click on the local computer icon --> Connect to another computer.
Then go into the removable storage icon and you can eject/inject media from there.
If you're doing it to a WAN IP you know that's somewhat illegal

But in theory it could be done the same way if you can force entry to their machine/they don't have a firewall, log in as the administrator then go through the removable storage and eject/inject it from there