By default, when you deploy a decision tree, it includes "Back" and "Restart" buttons.  You can enable or disable these for your entire tree, or for individual nodes.

"Back" and "Restart" may appear like this:

Note: Back and Restart won't appear in the first node of the tree, except in Preview.

Enabling Back and Restart for the Entire Tree

In the Settings tool, under the Display tab, you can show or hide Back and Restart as follows:

Disabling Back and Restart for Individual Nodes

You can also hide these buttons when a particular Content Node is displayed. Just edit the node, and go to the More tab.