I currently have access to my printers through octopi. Everything's working great.
I'd like to move my printers to another location with a different Wifi network.
I know I can plug the SD cards into my PC and edit the credentials with a text editor. But I have 5 machines, and it requires a little disassembly to access the SD cards.
So my question is, is it possible to edit those credentials through octopi, without physically removing the SD card?
If they are currently connected to a WiFi network, you can edit the file over SSH.
Running sudo nano /boot/octopi-wpa-supplicant.txt will allow you to edit it. You can duplicate the network blocks to add additional networks, so when you move it the Pi will choose the first available.
I haven't used SSH before, would you mind breaking down the steps? So far it looks like you use something like PuTTY, connect to the IP address... and then send that command in the portal. Am I on the right track?
I have jobs running at the moment, otherwise I'd have jumped in already and tried it. 
That's one way - check this guide out to see another 
and since you never used ssh a little hint in advance:
when your'e done with editing the file press CTRL + x to close the texteditor.
I will ask you then if you want to save the file which you can approve with y followed by enter.
Restart the pi with sudo reboot
This was super helpful, thank you both!