Option to deactivate WhatsApp as soon as your phone is lost. For this you have to send a mail to WhatsApp support. For this you need to send a mail to support@whatsapp.com mail id explaining that your phone is lost and deactivating the account.
In this you have to mention your phone number. But your mail id should also have the same phone number link.
If the phone is lost, the question of chat history also arises. There is an idea for this too. You can restore the chat history even if your phone is lost if you backup your WhatsApp account chat from time to time. You can get a backup if you change the settings so that the chat is backed up from time to time. For this you have to go to WhatsApp settings, select chats option and click on chat backup.
You should block your old phone number as soon as you lose your phone. The telecom company will immediately provide a new SIM card. With this, you can log into WhatsApp again with a new SIM card and restore the chat history. You can log out from the old phone and log in on the new phone.
If your phone is lost, two step verification should be enabled to prevent others from accessing your WhatsApp account. For this, open WhatsApp app and go to settings. After that, you have to select two step verification in the account section. A six digit code should be set immediately. With this, you have to enter the PIN while opening WhatsApp. With this, when you open WhatsApp, WhatsApp will open only if you enter the 6-digit PIN.