PostgreSQL installed wrong, how to uninstall it

I was following a tutorial to learn PostgreSQL. I wanted to install it under Users/myusername on mac. So I can log in to my account, and then start and use PostgreSQL. But something went wrong. How to delete PostgreSQL without reinstalling my computer? I succeeded later in installing PostgreSQL under Users/myusername, but it says port 5432 is already in use. I can't recall the details of the weird installation. enter image description here