Deleted account not available any more

No answer so far... Is it the right place to ask such a question?

how to deleted
1) with GUI Account Control?
2) with command userdel
3) with command deluser

its difference switch
example
all deleted data or just delete the account

@kokoye2007, this is a question about Launchpad accounts, not Ubuntu accounts. That advice is not applicable here.

This is the right place to ask this question - sorry we haven't got around to figuring out the correct answer in this case yet, but we will.

Sorry for the delay. I've renamed the old account out of the way, so you should be able to reclaim the username now.

That worked out! I could create the username "cyberbotics" on launchpad.net. Thank you.
However, I cannot use this account to log-in at snapcraft.io, once I log-in, I get the following error:

Bad Gateway
Please try again later

You can check the service status at status.snapcraft.io.

If the problem persists please check the Snapcraft forum or report an issue.

Can you help me with that?

That isn't something we can help with at the moment. You seem to already be in touch with a member of the web team on the snapcraft forum, and hopefully they can work it out (which may involve coming back to us, but they should be able to extract more debugging information first).

We're handling the snapcraft.io situation directly with the user (profile mismatch due to the account deletion/recreation), so this question can be considered closed on the Launchpad side :)