After a username is created, it is not possible to change the username anymore.
A new username can be created for you with the correct username (and delete the old username if needed).
If you delete a user - this has consequences if the user has the user role 'restricted client user' or 'authoriser'. A restricted client user can only view the documents that he/she delivered to Basecone (in the archive) and an authorizer can only view the documents that he/she has approved (in the archive).
When the users are deleted and he/she logs in with a new username - the user will not be able to view the documents that the he/she has previously delivered to Basecone. He/she can only view the new documents that he/she delivers to Basecone.