First Cymru said the ftrMetro is too expensive to run.
Major roadworks costing about £10m were carried out in the city to accommodate the buses including on The Kingsway.
The road layout was criticised by a coroner earlier this year for having a "serious design issue" after two people died.
Businesses on the road said the works hit trade "more than the recession".
Swansea council said the decision would help it improve traffic flow along with its plans to regenerate the city centre.
When the changes were made, a roundabout at one end of The Kingsway - which included underpasses - was filled in while a flat one at the other end was removed.
One side of the road was changed to a two-lane one-way system for normal traffic. The other side was changed to a two-way system for buses and taxis.
Justin Davies, managing director of First Bus Cymru, said the ftrMetro had worked well since it was introduced in 2009 but more efficient buses will now be used.
He added: "Since their construction, engine technology has improved considerably with improved fuel consumption and lower maintenance costs.
"In light of these factors coupled with reduced fuel rebate and reductions in the funding for concessionary customers, the decision has been taken to withdraw the ftrMetro articulated buses from service."
A Swansea council spokesman said: "It allows the council to incorporate these changes into the redesign of the city centre to improve traffic flow and the overall offering for traders and visitors.
"In the shorter term it helps us to redesign traffic flows with greater flexibility so that we can address the current issues along The Kingsway."
Bendy buses which were introduced six years ago and led to controversial changes to the road system in Swansea city centre are to be scrapped.