There are very few circumstances where suicide is cowardly. I.e killing yourself because you don't want to face the people you have screwed over through deceit and manipulation for your own gain. Killing yourself in this case would be a cowardly way of dealing with the wrongs you committed.
I think Hitler's ( Godwin's Law Ding Ding Ding) suicide was a cowards way out - he couldn't face the music.
Aside from that, whether or not it is right or wrong, suicide takes bravery to jump into that great unknown knowing you will never come back.