Simplify the following text for a Grade 13 native English-speaking person.
Original: Further , and contrary to his pledge during his first election campaign , when he said `` only a de-humanised moron would get rid of the Routemaster '' , Livingstone removed the famous Routemaster buses from routine service on 9 December 2005 , claiming it was because the new buses were wheelchair-accessible , although several of the old buses are used on shortened `` heritage routes '' .
Simplified: Livingstone also removed the famous Routemaster 1950 's buses from routine service on 9 December 2005 , claiming it was because the new buses were wheelchair-accessible , although several of the old buses are used on shortened `` heritage routes '' .