You can add a new printer directly from your back office. If you will access your Back Office from your iPad, you simply go to Settings ⚙️> BackOffice, in the case you will access with your computer, open your browser and type: https://app.tillersystems.com/ 

Once you log-in to your back office, click on Configuration. Subsequently, click on Your Printers. On the upper right corner click on the green rectangle New Printer

You will have to give a specific name to the printer (eg. Kitchen, Bar) and select the product categories you want to assign to the new printer simply by clicking on the category name. To save your changes click on Add

In order to delete an existing printer simply click on the red cross to the right of the printer name. Finally, click on submit to delete the printer.