How to sell my fathers self acquired property

it is regarding selling of my father's self earned property Partition deed which was executed on 2004 clearly says, ground floor belongs to me and first floor belongs to my elder brother. From 2004 onwards, for both the houses, we are paying property tax through a separate khata to mahanagar palike. My father is alive and about 90 years of age and living with my elder brother. now we both brothers wants to sell the property together (both ground floor and first floor) I have one sister who was also a consent witness for the partition deed and signed in the partition document which