Dear Friends:
How to retract the two dragged handles of a node to intersect again and become a sharp point? It’s almost impossible to do this by using the mouse.
With the paths tool active:
Click on the control point to expand the tangents.
Hold shift-ctrl down (that is edit mode and the tool icon has a minus sign)
Click on the end on a tangent to collapse it. Repeat for the other tangent.
example: https://i.imgur.com/uwUpRoC.mp4