Updated version of the tweet deleter and retweet undoer for the 2019 version of Twitter.

deletealltwitter.js

var deleteall = async function() {
	console.log("Undoing Retweets")
	// Keep iterating until there's no retweet to do
	while (retweet = document.querySelector('[data-testid="unretweet"]')) {
		console.log(retweet)
		retweet.click();
		// Sleep a bit to make sure the confirm prompt appeared
		await new Promise(r => setTimeout(r, 1000));
		document.querySelector('[data-testid="unretweetConfirm"]').click()
		// Sleep a bit again to make sure the tweet is unspawned from view
		await new Promise(r => setTimeout(r, 1000));
		// Scroll until the end to make sure more things are loaded
		window.scrollTo(0, document.querySelector('[data-testid="primaryColumn"]').clientHeight);
	}
	console.log("Deleting tweets")
	while (tweet = document.getElementsByClassName("css-1dbjc4n r-sdzlij r-1p0dtai r-xoduu5 r-1d2f490 r-podbf7 r-u8s1d r-zchlnj r-ipm5af r-o7ynqc r-6416eg")[0]) {
		console.log(tweet)
		tweet.click();
		// Sleep to make sure the menuitem spawned
		await new Promise(r => setTimeout(r, 1000));
		document.querySelector('[role="menuitem"]').parentElement.firstChild.click();
		// Sleep a bit to make sure the confirm prompt appeared
		await new Promise(r => setTimeout(r, 1000));
		document.querySelector('[data-testid="confirmationSheetConfirm"]').click();
		// Sleep a bit again to make sure the tweet is unspawned from view
		await new Promise(r => setTimeout(r, 1000));
		// Scroll until the end to make sure more things are loaded
		window.scrollTo(0, document.querySelector('[data-testid="primaryColumn"]').clientHeight);
	}
}
// Run it
deleteall();