I've had a lot of questions about how to go about this so I'm going to put some instructions here. All members have the ability to change their display names. Navigate to your profile page here on the forum and under Preferences you should see a field with your current display name. Replace it and click the checkmark when you're finished. If you're on Slack with us, you'll need to ensure your display name there matches the one you use here on the forum.
As for username changes, you will need to contact me to do that. You can shoot me a PM here on the forum. (Note: I am not always the fastest about this and you may have to hound me about it )
Lastly, if you want threads deleted, you need to rename them to "delete please" and flag them so I know where they are.