For the purpose of making the game more enjoyable, I think it is necessary for the players to be able to deactivate certain constellations for characters. It’s pretty easy to activate them but once that is done there is no going back. Which is why I think it’s pretty important to allow the players to decide which constellations they want to keep activated and which they want to deactivate. 

Some constellations in the game are considered bad (especially Bennett’s C6) and these could ruin a player’s gaming experience. But some people might still enjoy these constellations and there is no guaranteeing that Mihoyo have the power to rewrite constellations for already released characters. 

This is why having an option that would allow us to deactivate constellations is a better solution to this issue.