If you want or need to control who can read your posts, you should urgently take steps to remove them from Mastodon* and switch to a secure communication protocol. I can recommend #Signal (https://www.signal.org) or #Matrix (https://matrix.org) for secure messaging and #Haven (https://havenweb.org) for private (micro)blogging.
Though note that there is no way of forcing people to honour requests to delete data. Copies will almost certainly remain somewhere, indefinitely.
osma
gratefulwolf