I'm a bad person. I should have just fixed the script in the repo of the original author, but opted to steal the TweetDestroyer module instead and wrap it with updated code to support the twitter json (not csv) - thanks @koenrh !

butchered-delete-tweets.py

from datetime import datetime
import json, os, twitter, io, time

string_input_with_date = "01/01/2018"
file_name = 'tweet.js'

TWITTER_CONSUMER_KEY=""
TWITTER_CONSUMER_SECRET=""
TWITTER_ACCESS_TOKEN=""
TWITTER_ACCESS_TOKEN_SECRET=""

class TweetDestroyer(object):
    def __init__(self, twitter_api):
        self.twitter_api = twitter_api
    def destroy(self, tweet_id):
        try:
            print("delete tweet %s" % tweet_id)
            self.twitter_api.DestroyStatus(tweet_id)
            time.sleep(0.5)
        except twitter.TwitterError as err:
            print("Exception: %s\n" % err.message)

api = twitter.Api(consumer_key=TWITTER_CONSUMER_KEY,
                  consumer_secret=TWITTER_CONSUMER_SECRET,
                  access_token_key=TWITTER_ACCESS_TOKEN,
                  access_token_secret=TWITTER_ACCESS_TOKEN_SECRET)
destroyer = TweetDestroyer(api)

inputDate = datetime.strptime(string_input_with_date, "%d/%m/%Y")
json_data = json.loads(io.open(file_name, mode='r', encoding='utf-8').read()[25:])
count = 0
for tweet in json_data:
	tweetDate = datetime.strptime(tweet['created_at'],"%a %b %d %H:%M:%S +0000 %Y")
	if tweetDate < inputDate:
		destroyer.destroy(tweet['id'])
		count += 1
print('Deleted ' + str(count) + ' tweets!')

Could you please write a detailed guide on how to use this script? Thanks