You'd need to sign up for a totally new account. There is talk of adding a migration feature but obviously that'll require a bit of patience, they've got a long list of feature requests!

[–] AgreeableLandscape@lemmy.ml -1 points 1 year ago

Unfortunately an account transfer feature is pretty complicated to develop so it might still be a while. Devs need to make sure it doesn't cause issues with federation when content changes home instances and domains, and transferring live user content over while retaining points, interactions by other accounts, and while having the same timestamp but now being hosted on a different instance, while ensuring there is only one canonical location/URL of the content on the fediverse, is not easy.