A private agreement usually contained in a deed or lease, which restricts the use and occupancy of real property, is a restrictive covenant.  Such a covenant is said to run with the land and binds all subsequent purchasers, their heirs and assigns.  It also normally covers such things as lot size; building lines, type of architecture and uses to which the property may be put. 

Restrictive covenants may generally be terminated by obtaining quitclaim deeds from all benefiting owners.  However, this may not be practical because the termination must be unanimous and the consent of the underlying mortgagees may be required as well.