All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If Allah bestows guidance upon one of His Servants, he should be kind towards those who are around him especially his family and relatives. So, if a member of the family does not perform the obligatory prayer, one should advise him in a good manner to do so and supplicate Allah to guide him to the right path and enable him to be steadfast on it.
So, what if this person is one of the parents as Allah has emphasized their rights; Allah Says (what means): {Worship Allah and associate nothing with Him and to parents do good.} [Quran 4:36]. Allah says in another verse clarifying that even if one of the parents is a non-Muslim or both of them are non-Muslims, good companionship is due to them from their Muslim children; Allah Says (what means): {But if they endeavor to make you associate with Me that of which you have no knowledge, do not obey them but accompany them in [this] world with appropriate kindness.} [Quran 31:15].
In any case, you should try to bring your father back home and be keep good company with him as long as you are both alive even if he abandons the prayer. Also, you should try to influence him with your good behavior without being influenced by his. However, if he asks you to do an act of disobedience to Allah, then you should not obey him as there is no obedience to a creature in disobeying the Creator.
Allah knows best.