Can you delete my key from the key server?
No, we cannot remove your key from the key server. When you submit a
key to our key server the key is also forwarded to other key servers
around the world, and they in turn forward the key to still other
servers. Deleting the key from our server would not cause it to be
deleted from any of the other servers in the world and so this is not
an effective way to ensure the discontinued use of your key.
And even if we removed your key from our keyserver, we would learn it
back from our peers within minutes.
What you can do however, is mark your key as "do not use". This is done
by revoking your key. Note that this requires access of the private key.
Refer to your OpenPGP implementation's documentation for details.