The carrier is the last U.S. airline to end the policy, which it first put in place in April 2020.
Delta Air Lines has said it will stop blocking seats on its planes starting May 1, the last U.S. airline to end the Covid-19-era policy as the travel industry begins to recover from the pandemic.
Delta first started blocking middle seats and limiting capacity on smaller planes in April last year. Other airlines had similar policies, but they have since gone back to selling all seats.
Delta and other carriers have repeatedly said filtration systems and intense cleaning make it unlikely that travelers will catch Covid-19 on a plane. But Delta said publicly that many travelers choose Delta over other airlines because it kept its policy in place.