End point: https://dev.twitter.com/rest/reference/post/statuses/unretweet/id
The source tweet.
But it accepting both the ids (source id / retweet id) , unretweet also successfull.
I’ve always done the source id, maybe it’s “smart” and knows what you’re trying to do with either one.
My thought process was always “I retweeted tweet id 123” If I changed my mind then “I want to unretweet tweet id 123”.
Thank you