Whoops, you got in too deep in a personal relationship. Wouldn't want to risk having a person in your life you connect with well and genuinely enjoy unconditionally, so now you have to start the process of getting out of that whole mess.
The best way to start, is to start is to see them less and less. Basically, find some reason to not see them in person. Maybe you take on a hobby that makes you more busy and as a plus, you start to develop a new skill. If hobbies aren't your thing, you could try something else to occupy your time with other things. You could read and study, go for drives, explore your surroundings, join a cult, or go to jail. Ease off the face to face time until you just slip away.
On the chance you don't have the luxury of just getting more busy, for example having a class together or being a part of the same group that meets regularly. A solid way is to ice them technologically. Do not send them anything and do NOT respond to anything. If you happen to be so bold, turn on your "read" option, so they know you read their messages, but decided not to respond.
Chances are, this person really gets you or got you at one point of time where you both really enjoyed each other. So, change your personality! Changing your personality can be very DIY, just never trust your gut instincts and go with the second or third choice you would make. If you don't think you can keep up an entirely different personality, there's always hypnotism. Changing your personality will (best case scenario) make the person think they just got to know you a little more and then realize you aren't who they thought you were. Or it'll send the message that you don't want to be around them anymore.
These tactics should work, but if they aren't, you can always move away without explanation. Ever get the urge to travel or to start a new life? Follow those impulses and get out of there. This is a good tactic, however, it's also kind of like giving up because you're trying to push them out of your life, not run away, so think hard about this before you go with it.
Another great tactic is to disagree with everything they say. A good tactic for meeting people is to match the energy, so when trying to unmeet someone just oppose the energy. Disagree with everything they say, say things you know will make them feel weird, throw everything you know about good conversation skills out the window, throw actual things out the actual window. Whatever you do just make it unpleasant.
Remember, you can't let people get too close because it releases control, so if anyone tries, they get da boot. ¯\_(ツ)_/¯
