This post might have some minor spoilers.

I just started the quest by speaking to Cass, and passed the 50 speech check. After that I'm told to clear the roads to some ranger or remove him, and since I'm playing a peaceful character I'd rather not kill the man. So the problems is I don't know what do I exactly need to clear? I headed north from the camp following the road all the way to Primm while killing some scorpions and Jackal gangers, everything hostile I came across basically.

Any help on how to proceed will be appreciated :fallout:

Follow your quest marker.

Boxing Gloves or Bean Bag rounds are the only way I'm afraid.

I forgot to mention that the quest marker points at the ranger, even though I already talked to him about clearing the road for the caravans.

Why is my only option to kill him? I should have a different option since it states so in the quest objectives, unless this is somehow bugged.

Yeah its bugged. Don't listen to the guys about killing him.
Your talking about the quest in the Mojave Outpost where you go kill ants right?
I think the only way to fix him is through using console commands. Disable and enable the guy and he will prob fix himself.