Is it permissible to sell or lease a residential apartment for commercial or administrative purposes, when a neighbor objects to that for fear of disturbance?

A neighbor does not have the right to prevent the sale or rental of an apartment. However, they do have the right to have any harm caused to them by the activities conducted in the apartment removed. If it is proven that a neighbor is being harmed by a certain activity, that harm must be removed. This harm could result from the exposure of neighbors' private spaces and peeking into their homes. If harm is proven, the cause of that harm must be removed, based on the Prophet's (peace be upon him) saying: "There should be no harm nor reciprocating harm." Everything that causes certain harm to a neighbor, and anything that reveals persons and images, must be prevented. The mere increase in residents and visitors is not, in itself, a harm, unless they gather at the neighbor's door or crowd them when entering or exiting.