how to unhook a connection point?

[jerrys]

After I drew a continuous line with many turning
points. I realized that at one of the turning points, the
line at one side needs to be thicker. And the line at
the other side needs to be thinner. So I have to
break the connection right at the connection point. Is this
possible? Which tool to use? And how to do it? Thanks.

 

[Michel LAPLANE]

Draw a line perpendicular to your continuous line and glued to the
connection point. Activate the cut tool (Shape=>Operations=>Cut). Delete the
broken perpendicular line, your continuous line is also broken.