implode_slack.rb

#!/usr/bin/env ruby

require 'net/http'
require 'json'
require 'addressable/uri'

@debug_messages = false

token = '[TOKEN GOES HERE]'
user  = '[USER NAME GOES HERE}'

def delete_user_messages(user, token)
  message_count, messages = get_messages(user, token)
  while message_count > 0 do
    delete_messages(messages, token)
    message_count, messages = get_messages(user, token)
  end
end
  
def get_messages(user, token)
  index_url  = Addressable::URI.parse('https://slack.com/api/search.messages')
  
  search_query = "from:#{user}"
  index_url.query_values = {token:token, query:search_query, count: 500}

  index = JSON.parse(Net::HTTP.get(index_url))
  puts "#{user} has #{index["messages"]["total"]} messages"
  return index["messages"]["total"], index["messages"]["matches"]
end

def delete_messages(messages, token)
  messages.each{|message| delete_message(message, token)}
end

def delete_message(message, token)
  delete_url = Addressable::URI.parse('https://slack.com/api/chat.delete')
  timestamp = message["ts"]
  channel_id = message["channel"]["id"]
  channel_name = message["channel"]["name"]
  delete_url.query_values = { token: token, ts: timestamp, channel: channel_id }
  print "Deleting message at #{timestamp} from #{channel_name}... " if @debug_messages
  begin
    resp = JSON.parse(Net::HTTP.get(delete_url))
    #print "#{delete_url}..." if @debug_messages
  rescue StandardError => e
    sleep(0.5)
    puts "Something went wrong: #{e.message}"
  end
  puts "okay, done" if @debug_messages
end

delete_user_messages(user, token)