From Birnam Designs Wiki

To rename a printer in Linux:

sudo vim /etc/cups/printers.conf

The config file lists printers delimited like:

<Printer canonmx300>
Info ...
Location ...
etc.
etc.
etc.
</Printer>

Rename the text after "Printer" within the < and > at the top of each definition.

DO NOT USE SPACES IN THE NAME it will make the printer inaccessible.

Save, close, and restart cups with:

sudo service cups restart