What is the ruling of Islamic law on accepting to privately tutor students from the Qur'anic Academy where I work, given a prior commitment not to do so, knowing that the parents wish to leave the Academy and that refusing private tutoring might affect their children's memorization?

What was pledged must be fulfilled, and the terms of the contract must be adhered to, for Allah Almighty says: "O you who have believed, fulfill [all] contracts," and the Prophet, peace and blessings be upon him, said: "Muslims are bound by their conditions." The departure of one of the academy's students does not negate the necessity of the condition; therefore, the questioner must either refrain from tutoring him privately or seek permission from the academy's administration.