Typically with any stain, the faster you send it to wash - the easier it is to get rid of it.

A popular method is to try lemon juice and baking soda; apply the baking soda over affected area followed by a squeeze of some lemon juice. The concoction should foam like soap and you should be able to clean it with a slightly damp cloth.
Having said that you'd definitely wanna test it out on some place inconspicuous first though to make sure it doesn't do anything else apart from leaving your sofa fresh and clean. For additional methods you may even refer to this blog post here!*

*Credit to www.today.com.