Stop WhatsApp from being used on lost phone I lost my Android phone, but my WhatsApp is still on. How I can stop someone who is using it?

I don't have the SIM with me. The people who found it is using my WhatsApp account. When they went online, I tried to talk but they did no reply.
From Whatsapp:


  What do I do if my phone is lost or stolen?
  
  In the unfortunate case that your phone gets lost or stolen, we can
  help make sure that no one can use your WhatsApp account.
  
  As soon as possible you should call your mobile provider to lock your
  SIM card. Then, it will not be possible to verify the account on that
  phone again as you need to be able to receive SMS or phone calls to
  verify an account.
  
  After you have locked the SIM in your stolen phone, you can use a new
  SIM with the same number to activate WhatsApp on your new phone. This
  is the fastest way to deactivate your account on the stolen phone.
  WhatsApp can only be activated with one phone number on one device at
  a time.
  
  If you are not ready to activate WhatsApp on a new phone with the same
  number we can deactivate your account. Email us with your phone number
  in the full international format as described here. Please note that
  we are not able to help you locate your phone. Remote WhatsApp
  deactivation from another device is not possible.
  
  Important: Even with the SIM card locked and phone service disabled,
  WhatsApp can be used on Wi-Fi if you do not contact us with an account
  deactivation request.
  
  More important details about deactivated accounts
  
  
  When your account is deactivated, it is not completely deleted.
  While your account is deactivated:
  
  
  Your name is still on your contacts' Favorites / Select Contact lists.
  Your contacts can send you messages, which will remain in a pending state for up to 30 days.
  
  If you reactivate your account before it is deleted, you will receive any pending messages on your new phone and you will still be
  in all of your group chats.
  If a deactivated account is not re-activated within 30 days, it will be completely deleted.
  
  
  Note: Since your chat history is stored on your device, we cannot retrieve your previous messages.