Also, donโt leave your account unused, delete it. User and follower numbers count.
And least as important, reply (if necessary to another corporate mail address) every email with Twitter/X in the footer, with a kind request to stop promoting and facilitating X.
Granted, if you have a sizable following there, you could try to get them to make Mastodon/Bluesky/... accounts to follow you off the platform first.
Of course, you should have done that years ago, but better late than never.
But if you have less than ... idk, 100 to 1000 followers? You should just switch.