She plotted a conspiracy to kill her husband King Al-Mu‘izz, who was actually killed in her palace in Rabee‘ Al-Awwal 655 A.H., thereby ending the realm of King Al-Mu‘izz after remaining seven years on the throne of Egypt. Shajarat Ad-Durr thus killed two sultans of Egypt: Tooraan Shaah and King Al-Mu‘izz ‘Izz Ad-Deen Aybak.

The murder was known publicly, and Sayf Ad-Deen Qutuz, the main assistant of King Al-Mu‘izz, along with Noor Ad-Deen ‘Ali, son of Al-Mu‘izz from his first wife, and a brigade of the Mu‘izzi Mamluks, hastened and arrested Shajarat Ad-Durr. The first wife of Al-Mu‘izz, the mother of Noor Ad-Deen ‘Ali, requested Qutuz to let her undertake by herself the execution of Shajarat Ad-Durr. She then received the famous tragic end. The mother of Noor Ad-Deen ordered her slave-girls to kill the previous queen, Shajarat Ad-Durr, by means of beating with clogs.

This incident of death was, almost, the only one which had a Sharee‘ah-accepted background. Shajarat Ad-Durr killed ‘Izz Ad-Deen Aybak with no just cause. Neither his marriage to another woman, nor his tendency to rule Egypt alone without submission to his wife could be regarded as a crime. This means that she had no pretext, under Sharee‘ah, to kill him. For this reason, she had to be killed. But, at the same time, it is also certain that she was not killed in a Sharee‘ah-approved way; it was rather a feminine way intended not only to kill her but also to humiliate and disgrace her as was the case with Al-Musta‘sim, the Abbasid Caliph in the wake of the fall of Baghdad, when he was kicked to death. Those very special ends are always doomed by Allah, the Almighty to some kings who do not observe the Rights of Allah and people in this World.

After the death of King Al-Mu‘izz, and Shajarat Ad-Durr, the pledge of allegiance was taken to Noor Ad-Deen ‘Ali, the son of King Al-Mu‘izz, who had not yet attained the age of fifteen. No doubt, this was a great violation. But it was intended to interrupt the expected dispute between the Mamluk emirs over the throne. The young sultan was titled Al-Mansoor, and put under the entire trusteeship of Sayf Ad-Deen Qutuz, the strongest of men in Egypt at that time, and the leader of the army and the Mu‘izzi Mamluks, and the most loyal to the late King Al-Mu‘izz. The pledge of allegiance was taken to the child in Rabee‘ Al-Awwal 655 A.H.
But the actual ruler of Egypt was Sayf Ad-Deen Qutuz, May Allah have mercy upon him.

https://en.islamstory.com/index.php/en/artical/20812/king-ll-mu‘izz,