I used to have "@matmuchrapna" username, but now you will find me as @iamstarkov. I successfully renamed myself on internet and want to share my experience. I’m assuming that you want to have the same username on domain, mail, social media and messengers. If you have trademark, skip entire article.
Top level domain '.com'
You can get domain username.com if it’s available or squatted. In case of squatting you’d better to have extra money. If username.com is available, then check this username on social media, because it can be squatted there too.
Mail (gmail in my case)
You can get username only if it’s available. In this case renaming is registering new account.
You can get username only if it’s available. Twitter support is awfull. You will not get any reply from them. Also you will not get username of suspended user. Twitter will not redirect users from your previous account to new one.
You can get username only if it is available or it’s owned by activeless user. GitHub support is awesome. GitHub will not redirect users from your previous account to new one, but will do it for repositories. All of the README’s badges will be broken.
npm support is great too, e.g. I got answers from Isaac Shueltz—npm’s founder. npm helped me with moving all the packages from prev account to the new one. Obviously npm deleted my previous account.
You don’t need to change anything here.
LinkedIn is great on renaming, easy and without any side-effects.
Don’t forget about avatar for the new email.
You can get username only if it’s available.
Like gmail — the only way to be renamed is to register new username.
Define list of social networks and list of usernames to check. Choose one, which is available everywhere. Renaming Gmail requires extra work.
Choose new name carefully,
your renamed Vladimir Starkov