You can use discuss in mailing list mode, which also is allowed here. Deleting the posts is not going to remove the email copies, which could be included in public archives.
We will never delete posts when removing accounts, unless those posts contain personal information (and we’re made aware of that). When anonymizing accounts:
The user will no longer be able to log in as this specific account.
A new username will be randomly assigned to the user such as anon123456. This new username will be applied to all their posts in the system, and we will update all @mentions and quotes too.
The new username is not applied to: deleted posts, post revisions when the current post doesn’t mention or quote the renamed user anymore, oneboxed user profiles, queued posts, or staff logs.
Their email, name, date of birth and avatar will be removed.
Their user profile will be removed.
Any api keys generated for the user will be revoked.
Any third party authentication mechanisms (Twitter/GitHub/etc) will be revoked.
I would very strongly discourage this, as it is only harmful to our discussions and provides 0 benefit to you.
I don’t believe anything would prevent username reuse, because we don’t retain any of this information.