If a person was a true rasha why would they attempt or truly want to commit suicide? Which rasha has a conscience? Which Rasha hates their life to a point that they would want to end it? A rasha loves doing what they do. They love causing misery to others, that is their enjoyment and that is their whole purpose in life to hurt others and to make others miserable. So why would a rasha contemplate suicide and another person have to ponder whether or not to save them?
On the other hand, if a rasha were in a situation where their life were at risk, then you can ask the question is one obligated to save the rasha? I am no chocham but I would imagine that one would be as obligated as one would be to any other person.