The word "de-orbited" used in the article seems to not be the normal use of the word. Normally if you de-orbit a satellite, you lower its orbit until it either burns up in the atmosphere or hits the Earth. Satellites in GEO don't de-orbit in this way because it would need too much extra fuel. Instead, when GEO satellites are decommissioned, they raise their orbit into what is known as the graveyard orbit.