Does anyone know how to change your registered name on websites?

Okay soo I am not worried about yahoo or things like that, for instance on my myspace page, my webshots, my photobucket etc... I always used the same name to register and when anyone goes to any search engine and for instance my registered name is ';joesmoo123'; they can type that in and see everything I have ever posted in a blog or a comment I have made on random sites... etc... I dont want everyone being able to see all of that, so I wanted to know how to get rid of it... Or how to delete or make private some of the stuff that I have posted and didnt know anyone could seeDoes anyone know how to change your registered name on websites?
Well since we are talking about the past, you can't hide any of that information. I am very familiar with search engines and coding and technically you can't hide it unless you are the Search Engine Engineer and then you could remove it from the server. Since you are not, I would suggest that you contact every single Search Engine and ask if they could remove your results. They might or might not remove your information. If you want to delete all your accounts with myspace, photobucket, etc... and then create a new one...Does anyone know how to change your registered name on websites?
I think you would have to contact your Internet Provider to answer this question.