Deleting those you like or those that like you?
Have not tired this with this revised format, but if it is someone you like and want to unlike, go to that profile, look for the green icon that shows you liked, clic on it, should unlike. Not sure if this lets the other know that you un liked them.
If it is someone that liked you, it shows up in your mail, just trash it. Then block if you have a problem. I do not believe you can unlike someone else's like. I do remember that on the activity page you could make "no interest". Not sure if that exists now.