There is no official way to do this. The Tweet delete endpoint is only something to delete some amount of Tweets and it is not intended for a complete wipe, so If you use it for this case (which is quite card, since there are rate limits), you might end up still seeing some of the Tweets as it might take a while until the servers fully updated/synced. But after some time, all Tweets should be gone, which were successfully deleted with the delete API endpoint. If not, this could be a possible API bug and some more information would be great.
