Is this a CityEngine question, or ArcGIS? In CityEngine this is not possible. I've wanted this also, so I just filed a feature request with the CE development team. So we may see it in an upcoming release. For now, just reconnect with a new road segment or connect the two leftover nodes.
Hi Steve, your issue can probably be solved by applying the next three steps.
1. Activate the move tool by pressing the 'w' key
1. Select the node that you like to delete
2. Drag it with your mouse onto one of the two neighbouring nodes
Good luck & Have a great day!