Naruto Uzumaki is a Shinobi of Konohagakure’s Uzumaki clan and the main protagonist of the very famous anime: Naruto. He is also known as
Bestowing Kakashi with two Mangekyō Sharingan was the doing of the spirit of Obito and not the physical self. So when Kaguya was defeated, Obito’s spirit left Kakashi’s side to join the other world, taking his Sharingan along with him.
Kakashi first used his Mangekyō Sharingan in actual combat in one of the initial episodes of Shippuden in Kazekage Rescue Arc during his fight with Deidara while performing Jutsu Kamui on him. He used it when he got fluent in using and controlling Mangekyō Sharingan after gaining a good amount of understanding and practice.
Kakashi cannot deactivate his Sharingan because it was a gift from Obito Uchiha, and only an Uchiha can turn the Sharingan on or off. The Uchiha have a specific gene that allows them to use, activate, and deactivate their Sharingan at will. Not only is Kakashi Hatake not an Uchiha, but the eye also did not belong to him as Obito Uchiha gifted it for becoming a Jonin. Kakashi’s strength is still great, and he can support his eye for an extended period. Despite this, he cannot turn off his Sharingan because his chakra will completely reset to zero.