ИДЕЯ ДЛЯ РИЗОМА

There are a lot of things I would like to undo. Some skills that I've used points in are completely useless for me. Of course there should be some kind of small price for unlearning skills (i.e. talking to an NPC and paying X dappers)

Also, there are some quests that I don't want to do anymore because it requires me to spend points in a skill that I don't want to spend points in. In all, I want it off my list.

There is no point in unlearning. In the grand scheme of things you end up with more skill points than know what to do with. Very soon you will be able to buy the skills you missed.

As Amnesia says, those seemingly worthless skills can become great assets later. You can also gain skill points in other related skills to buy up those things you've missed.

This makes me think that you are still on Silan where you cannot abandon missions. You can't abandon missions on Silan but you can on the Mainland.