Praise be to Allah.
The basic principle concerning the kaafir when he dies is that his relatives should bury him in a grave so that he (the body) will not harm or disturb other people. He should not be washed or shrouded, and no prayer should be offered over him. Whoever does anything other than that or takes part with the kuffaar in their customs has to repent and seek the forgiveness of Allaah, and hope that Allaah will accept his repentance.
And Allaah is the Source of strength. May Allaah bless our Prophet Muhammad and his family and companions, and grant them peace.