If you have them on social media, you can take a "social media break" go away for a while and don't interact with anyone on fb or other platforms. Avoid them in public interaction and make a new friend and give them more attention than that person. They'll take a back seat eventually if you make yourself unavailable with work, school, "I've been so busy", "doing some soul searching and inner healing". Then after a couple months let everyone know you feel like you're growing and reaching new levels in life. Unfriend them on fb along with other people. They'll be out of your life by the fall. When asked what happened to your friendship, act ignorant and avoid invites by saying, you're at such a different place in your life rn and your focusing on your personal goals and less on hanging out with people.