[2020] Dwarves - Dwarven Portal, Granite Mines & Copper Foundries

Greetings @StrawberryJC Don't do it just yet!! As you move into the Chapter you'll receive a quest to do this with a nice little gift for doing so  

@StrawberryJC absolutely, the quest will tell you directly to sell the portal. Once you complete all the quests from dwarves, you will receive a "delete the portal" quest You will not need it anymore.

Make sure to finish your roads first, or hold onto some copper and granite to road-up later. Even if the dwarves tell you they take everything, and your portal is gone, you still will have the resources. In fact, even if you change to fairies and you no longer see them, you still have these resources.