Elton John is selling his apartment at West Hollywood’s storied Sierra Towers and is looking for an LA mansion. Sources tell us Elton, who owns two adjoining units in the celebrity-magnet tower, wants to buy a house where he and partner David Furnish can bring up their son Zachary. Furnish commissioned designer Martyn Lawrence-Bullard to create a 1970s-inspired design for the apartment which features kelly green walls and a chandelier from the Grand Hotel in Milan in the kitchen. Other residents in the 31-story tower, in which apartments go from $2 million to $9.5 million, include Joan Collins, Cher and Courteney Cox. A spokeswoman for John confirmed he is selling his apartment.