Open the song you'd like to print.
Tap the Share button in the top right corner (square with an arrow).
Tap Export Chord Chart

- For AirPrint enabled printer
Tap Print
[Or If you have a keyboard connected, simply use cmd-P (the normal Apple Print key command)]

- To print from your computer
Email it to yourself (Mac users can use AirDrop) then print from your computer

If you want the chord diagrams in the chart, turn on the Chord font you want, here is how.

In case you have a chart that has only 4-5 systems, the printer might default to landscape.
Open the Editor and add an extra character 2-3 lines under the last bar to make sure the chart will be printed in portrait.