How can one get rid of the habits of lying, delaying prayer, backbiting, stealing, and sins acquired since childhood? And will a person be held accountable for sins committed in their childhood?

What a person did before reaching puberty is not accounted for. Getting rid of deviations is made easy through supplication (du'a), strengthening faith, keeping good company, and resolving firmly to abandon them. This also involves reflecting on the texts of the two revelations (Qur'an and Sunnah) that clarify their dangers, and remembering the torment of the grave and the Hellfire. Sincere repentance is obligatory, as is seeking absolution from those whose rights were violated, increasing good deeds, and occupying oneself with truth, such as calling to Allah, seeking knowledge, and serving the interests of the Muslim community.