Method and apparatus for removing a downhole casing from a well on a single trip. A downhole tool assembly is arranged on a work string having a downhole pull tool, a spear tool, motor unit and cutting device. The downhole pull tool is set inside a first casing string and the spear tool, motor unit and cutting device are located inside a second casing string, located through the first casing string. The downhole pull tool and spear tool can be configures to grip the respective casings during cutting of the second casing string. The cut casing section can then be pulled using the downhole pull tool to dislodge the casing section, whereupon via attachment to the spear tool, the cut casing section can be removed from the well. The assembly can be re-set at shallower depths in the event that the cut casing section cannot be dislodged for removal.