Let's say I decide to start Baldur's Gate 3 with a group of 4 people and one of them decides they don't want to play anymore. What happens to that player's character? Is there a way to remove them from the party?
Patch 2 has come out recently, and now there is a way to remove the characters, by talking to Withers in camp once you have recruited him:
Introducing Withers’ Wardrobe of Wayward Friends! With this woodworked wonder, you can now dismiss co-op party members and bring your companions back into the fold.