Make sure you have the node selected in the editor, then click on a
single colour chip in the node editor window - it should highlight -
then press delete. Only that chip will be removed. If you haven't
selected the chip, the node and its output edges remain selected so
pressing delete will delete the node and all its output edges, hence
causing all the chips to be removed as well.
If you don't want an edge to fire, then delete the edge (click on the
edge, make sure it is the only thing selected and hit delete).