The Canon Print Centers ("Copiers") save trees by printing two-sided. But sometimes you need to print one-sided. Here's how.

With your print dialog box open:

If your print dialog is small, it is collapsed. To expand it, click the up and down arrows past the printer selected.
Now navigate to the middle of the screen and change the Layout options to the Finishing options.

On the finishing screen, you should see it set to two-sided printing:

And toggle it to 1-sided printing:

Now unless you want to do this every time you need to print one-sided, do not press that blue print button in the lower right corner. Let's save this as a preset, so we can quickly toggle to it without going through all this rigmarole.

At the top, under presets (second setting from the top), click the up and down arrow

Click on Save Current Settings as Preset... (the third option down):

You can call it what you like, but make it something that will remind you that this preset prints only on one side of the paper. I chose "Print Single-Sided"

Now press that print button.

You No Longer Have To Do This Every Time You Print

From now on, when you print, simply toggle the Presets: (second field from the top, directly below the Printer selected) to "Print Single Sided" and then press the print button.