•
Go into Curve mode 
.
• Move the dot in the curve cursor over a Marked Point that is part of a Curve.
• Click on the right mouse button. The Curve Right Menu will appear.
• Pick the "Remove point from curve" entry. The Marked Point will not be deleted but will be removed from the curve. The curve will redraw to take that into account.
Note that if a point being removed is part of two curves the Which Curve Dialog will appear. You pick the curve
and the point is removed from that curve only.