How to remove Line trace

I have moving two ball point and connected them

But, like following figure, trace remain

How to remove line trace

[Walter Roberson]

What is the maximum number of them that you want to exist at one time? For example, do you want the most recent 5 to be visible? Or do you want to draw all of them as you go but afterwards want them to start disappearing from the oldest, with there being no maximum number at a time ?