gistfile1.rb

require 'nokogiri'
require 'json'
require 'open-uri'
require 'oauth'

# Exchange your oauth_token and oauth_token_secret for an AccessToken instance.
# https://dev.twitter.com/apps here
def prepare_access_token(oauth_token, oauth_token_secret)
  consumer = OAuth::Consumer.new("Consumer key", "Consumer secret",
    { :site => "http://api.twitter.com",
      :scheme => :header
    })
  # now create the access token object from passed values
  token_hash = { :oauth_token => oauth_token,
                 :oauth_token_secret => oauth_token_secret
               }
  access_token = OAuth::AccessToken.from_hash(consumer, token_hash )
  return access_token
end

access_token = prepare_access_token("access token", "Access token secret")

url = 'https://api.twitter.com/1/friends/ids.json?cursor=-1&screen_name=khakimov' # use your user_name =)
doc = Nokogiri::HTML(open(url))
doc2 = JSON.parse(doc)

doc2['ids'].each do |id|
  p "#{id}"
  response = access_token.request(:post, "https://api.twitter.com/1/friendships/destroy.json?user_id=#{id}")
end