Moving or leaving accounts
Take your information and do what you want with it.
At any time you want, you can go to Settings > Export and download a CSV file for your current followed accounts, your currently created lists, your currently blocked accounts, your currently muted accounts, and your currently blocked domains. Your following, blocking, muting, and domain-blocking lists can be imported at Settings > Import, where they can either be merged or overwritten.
Requesting an archive of your posts and media can be done once every 7 days, and can be downloaded in ActivityPub JSON format. Mastodon currently does not support importing posts or media due to technical limitations, but your archive can be viewed by any software that understands how to parse ActivityPub documents.
From the bottom of Settings > Account, you can find options related to account redirection or migration.
Redirecting your account disables posting from that account and displays a “profile moved” notice indicating your new account. Anyone viewing your profile can see this notice and will know to follow you at your new account. Following redirected accounts is not possible. The redirect can be canceled at any time.
Moving your account is the same as redirecting your account, but it will also irreversibly force everyone to unfollow your current account and follow your new account, if their software supports the Move activity. Your posts will not be moved, due to technical limitations. There is also a 30 day cooldown period in which you cannot migrate again, so be very careful before using this option!
Profile moves can only be initiated when your two accounts have been aliased. Account aliases are currently not used for anything other than profile moves, where you will need to set your old account as an alias of your new account before initiating the move. Setting aliases is harmless and reversible on its own.
From the bottom of Settings > Account, you can find the form to delete your account. Deleting your account is irreversible, and will cause both your profile and username to become forever unusable.