A star's life is defined at the period during which its core fuses hydrogen into helium through the process of nuclear fusion. In comparison to other stars, a hypergiant has a much shorter life span because it depletes its hydrogen core much quicker (despite having more initial hydrogen than smaller stars, the hypergiant's denser gravity causes a higher rate of fusion). Once the hydrogen has been depleted, the hypergiant's core becomes a shell, and the initial composition of this shell is helium.
The helium shell of a hypergiant star is not a permanent state because the shell is still extremely hot and extremely gravitationally dense -- the two requirements needed for nuclear fusion to continue. As a result, the helium will continue to fuse into more dense elements, including oxygen and carbon. By the time the shell is burning oxygen and carbon, it has ejected much of its outer material (including any remaining helium), and the shell is extremely dense.
The carbon and oxygen of a hypergiant star will eventually fuse into iron. Once a hypergiant shell is primarily iron, it is too heavy to continue nuclear fusion, at which point the star collapses in on itself and explodes in a supernova. The supernova creates shock waves that send the star's remaining material out for several light years. This material, along with the outer material that had been previously ejected, is recycled into a nebulae, where gravity will eventually cause it to congeal and form new stars.
Even after a supernova, there are still possible remnants of a hypergiant star's shell. One possibility is a neutron, which is an extremely dense and compact form of the shell. A neutron star is not made up of individual elements, but of neutrons, which are neutrally charged particles. Another possibility for a hyper giant star's shell is that it could become a black hole, which is a point in space that is so gravitationally dense that nothing (not even light) can escape its pull.