From the print screen on the computer under the Printer name, select the Printer Properties.
Then, in the Printer Properties window, select Simplex from the Duplex drop-down menu.
You can also change your document to print single sided directly from the printer! You just need to log in to the printer, select your document/file, and choose the Options button at the bottom of the touchscreen. Here you can choose the Simplex option so your document will print single sided instead of the default (double sided).