In Islam, parents bear the responsibility to bring up their children according to the Islamic way. If they d
o that they will be blessed in this life and in the Hereafter, and if they don’t, they will get bad result during their life and in the Hereafter.
The Prophet (peace and blessings be upon him) is reported to have said: “All of you are guardians and all of you are responsible for things under your guardianship; the ruler is a guardian (managing his state’s affairs) and he is responsible for things under his care, the man is a guardian over his family and responsible for them, the woman is a guardian of her husband’s house and she is responsible for it. All of you are guardians and responsible for things under your control.” (Reported by Al-Bukhari and Muslim)

Sheikh Muhammad Iqbal Nadvi, Director and Imam of Al-Falah Islamic Center, Oakville, Ontario, Canada, states the following: Islamically the person becomes responsible for his or her actions after reaching the age of puberty, which can start even before the age of 18.

After this age, the person is responsible for his or her own actions, but parents are responsible to guide their children and help them start their life in a good way based on the teachings of Islam and the experience of life. Therefore, parents are recommended to help their daughters and sons get married if they can afford this. Kicking a child out at the age of 18 is not an Islamic manner.
as for staying with the parents in the same house, it is legally acceptable that a child leaves the house after the age of 18, but Islamically there are other concerns that are involved. The girl, for example, is not allowed to live by herself without having a mahram, and for the boy if there is no need for him to leave the house (such as his job or study, etc.) then he is supposed to take care of his parents until he starts his family life when he can move.
The point is that though Islamic accountability starts with the age of puberty, the law of guardianship does not end at this time, it continues to apply until marriage.