Is the questioner sinful if he leaves those he lives with who are negligent in prayer and do not pray except late, or abandon some of the obligatory prayers, after he advised them and they did not respond?

Delaying a prayer beyond its prescribed time and abandoning it without a valid excuse is among the gravest sins. In fact, some scholars hold the view that intentionally abandoning even a single prayer until its time has elapsed constitutes major disbelief (kufr akbar). It is obligatory to advise and remind those who are negligent in prayer about the seriousness of their actions, and to verbally denounce them. If they do not respond to advice, then it is preferable to distance oneself from them and avoid living with them, lest one who sits with them be influenced by them.