Finally after years of complaining from longtime Playstation users about changing your PSN ID, In early 2019 Sony will allow you to change your ID as a part of the Playstation Preview Program according to their post.
During the actual program, you will be able to change your online ID as many times as you see fit. The first change will be free, and after that it will be $9.99. If you are a PlayStation Plus member, it will be $4.99. You will also have the option to show your previous ID with your new ID if you change it so your friends can still easily identify you.
Please note that not every game will support this feature. Games published after April 1st, 2018 will support this feature. You can also revert back to your original ID for free if you don’t like it. I might have to change my online ID myself when this becomes active.