If away all of Pesach do you need to sell your house to a gentile, just sell your chometz at your house
or do something else?
All of the chametz is sold to a gentile, one of the methods of transaction is to lease to him a small part of one’s apartment or home. For one who is leaving his entire home for the duration of Pesach, the entire home may be leased to a gentile and all the chametz in the home sold to him, thus absolving him from cleaning and performing bedikas chametz on his home.
For one who will not perform bedikas chametz in another location, many leave over a small portion of the home on which to perform the bedika.