I have looked allover but I must have missed how to edit my name. I think I used my Google account to sign into area 51Buddhism if that helps.
I started with an unregistered account called Samadhi, couldn't log in and I register another account with the same name Samadhi. It is possible to merge the two account into one seeing that I've accumulated some points in my first account.
1Hi Samadhi, welcome to the site. I see you have three accounts (i.e. your answers here, here, and here). Apparently there's some software which should run automatically, and detect and merge the accounts; but I don't know how regularly that software is run. I asked one of the SE staff and they suggested that you request a merge using the Help Center > Contact form, with topic "I need to merge user profiles".– ChrisW ModMay 19, 2015 at 12:30
Your profile is displayed at https://buddhism.meta.stackexchange.com/users/151/user535875 (for meta) and/or at https://buddhism.stackexchange.com/users/151/user535875 (on the main site).
The two should be linked, editing one should edit the other; but you cannot edit your meta profile, therefore edit your profile on the main site.
On the 2nd line of the (main site) profile page, to the right of your name, immediately under the line which says "Questions" and "Tags" and "Users", there are links which say "edit" and "privileges" and "preferences".
That "edit" link is what you want to click.
That will probably take you to this URL which will let you edit your profile: https://buddhism.stackexchange.com/users/edit/151