There will be times when you need to end a relationship for whatever reason. The reason could be that you found someone new. It could also be that you are moving far away and you don’t want a long distance relationship. No matter the reason, you should never end a relationship with a text message.
It should always be in person in order to talk things out. The only times when a relationship can end instantly without face-to-face contact is when the relationship was abusive or you feel threatened or fearful of the person. Otherwise, it is important to think things through about what you are going to say, then meet with that person and discuss the situation in a quiet place.