Is it obligatory for the reciter to return to his original voice in reciting the Holy Quran and abandon imitating Sheikh Mishary Al-Afasy, after mastering the imitation and then considering it a temptation that places him between the choices of Islam or misguidance?

It is highly unlikely that imitating the Sheikh's voice would lead to disbelief (kufr), hypocrisy (riya'), and manifest misguidance, and that abandoning it would restore one's Islam. If imitating the Sheikh is indeed the sole cause of what has been mentioned, then one must retract it, for hypocrisy nullifies deeds, and disbelief is a sin Allah does not forgive except through repentance. Therefore, one must rid oneself of these two sins by any available means.