How to close the track builder

So, yeah - today I accidentally clicked the track-builder button which automatically inserted a track-item without any hint how to close, and remove the item / track-part. Clicking the remove-track-part trash-icon doesn't do anything and theres nowhere any "X" to close the track-builder? Can somebody pls help me? Or am I just blind?

 

press escape and hit the red arrow at the bottom of the sidebar

 

https://www.beamng.com/threads/exit-track-builder.63808/