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

@voltronic sincere question. What is the point of this if the internet is forever and all of your old tweets are findable in the archives?

@JenSemDem
This removes everything that is publicly viewable on your account. You may or may not be able to view an account's deleted tweets using Wayback Machine or other tools, but it would take some real effort for someone to scrape all of your deleted posts.

@voltronic understand, and sorry if I’m dense, but what is the value of removing all of your publicly visible posts? I’m not ashamed of anything I’ve posted, and want to spend less time there because I don’t want to support Ewok in any way. Is there hidden value in deleting my old posts that would cost him money or advertisers? :)

@JenSemDem
Good question. A couple reasons:

1. It reduces the attack surface for someone who would stalk / harass / social engineer you. Having less of yourself out there in the open is generally a good idea for the safety of you and your family.

2. Employers look into candidates' online histories, and you may have said something insensitive or inappropriate, or something innocent that can seem improper when taken out of context.

https://www.wired.com/story/the-know-it-alls-should-i-delete-my-tweets/