A simple quality of life change. Give players the option to 'drop' a side quest. The option would reset progress made, and remove the quest from your spell book. If a player wanted to pick the side quest up again, they could use quest finder, and it would take them back to the last person they talked to, and give them the option to accept or decline the quest again.
Not everyone wants to do the side quests in the game, and sometimes you pick them up by accident. Giving players the option to drop a side quest is simple and a pleasant addition.
