Script to backup and delete old tweets.
Go to http://dev.twitter.com. Create a new application. Call it for example "remove-tweet", use the description you want, and specify any website.
When it's done, go to "Settings" > "Application type" and specify "Read, Write and Access direct messages" (at least Read and Write). Validate.
Once everything is ok, come back to "Details" and create a new access token.
Now, modify settings.yml with the values specified in dev.twitter.com.
$ bundle install
$ ruby backup.rb
To go further the 3200th tweet, you have to fill a formal request to Twitter, then use the data to delete each tweet by its id See https://www.privacyinternational.org/blog/what-does-twitter-know-about-its-users-nologs You may have to be resident in the EU for that.