Take the cushions off the sofa. Remove all of the fabric covers that you can from the cushions and sofa.
Take the fabric covers and cushions outside if the weather is nice.
Fill a spray bottle with one part white vinegar and three parts water. Generously spray the covers and cushions with the white vinegar. Spray the sofa with the same vinegar solution. Open the windows in the room where the sofa is located.
Leave the cushions and covers outside until completely dry. Return the cushions and fabric covers back to the sofa and reassemble.