At the moment, we do not have the option to print your family tree on the MyHeritage mobile app. However, we've received many requests for this and we are planning to add this option in the future.
In the meantime, if you would like to print your family tree, you can do this on your family site online or in the Family Tree Builder software.
For more details please read the following articles:
How do I print a chart that I made in Family Tree Builder?