FOr cards like the one shown above can i discards him out of play after he has already skirmished or is about to or do i have to discard him from hand?
You discard him out of play before or after (if he survived ) he has skirmished.
Actually you can discard him in ANY skirmish phase, including his own. As long as you can pay the cost of the action (discard this minion) you are allowed to perform that action. Even if discarding him in his own skirmish won't have any effect.
I'm not stupid. I'm just unlucky when I'm thinking.