Such is a restriction to limit identity confusion and prevent abuse from spammers and the like. However, usernames are not assigned, they're chosen - if you don't actually like the one you chose, you have to create a new account.
Sorry.
John
I don't like my assigned name . Do I have to delete my whole cenet account to get rid of it ? I will delete everything that has anything to do with Cenet If I can't change the assigned name.

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