I'm seeing this in couple cases when using ui-text (to play around and lerning) that even after the deletion of the ui-text node the text is rendered in the group. I have restarted node-red and refreshed the pages, but it does not help ? Bug or Desing ? Only way have have been able to correct is delete the group and re-create it .
You're not the forst person to have mentioned this if I recall correctly, although I've still not seen a GitHub issue with repeatable steps so that I can investigate further. If you wouldn't mind dping the honours, it would be most appreciated.