For those leaving Twitter, you should keep your account there open for the reasons @kel suggests, but you might want to "zero it out". To do this:

1. Bulk-delete your tweets. (Note that the archive procedure described here is required for deleting ALL your tweets; otherwise Twitter API only allows access to the last 3200.)
https://tweetdeleter.com/features/delete-tweets-from-archive

2. Remove retweets with the "Using a Script" option here:
https://www.alphr.com/delete-all-retweets-twitter/

3. Remove favorites:
https://jeffreifman.com/2018/04/12/how-to-delete-your-twitter-favorites-with-javascript/

#cososec