To register your new phone, insert a SIM card with the same number. The easiest method to cancel an account on your stolen phone is to use the same number on a new SIM card. On one device, WhatsApp may only be used with one phone number at a time.
You must first launch WhatsApp and select the three-dotted symbol in the top right corner. Select Settings, go to Account, and then choose Delete My Account from the drop-down menu. After that, you’ll need to provide your phone number along with a final tap on Delete My Account.
How to Delete Your Google Account from WhatsApp. You can remove your Google account from WhatsApp by going to the Google Drive site, clicking the cog symbol, selecting Settings, selecting Manage Apps on the right, clicking Options next to WhatsApp Messenger, and then clicking Disconnect from Drive.
When you’re in WhatsApp Web on your computer, you’ll see a menu button (three vertical dots) at the top of the screen beside New Chat. After that, choose Log out from the drop-down menu. That will log you out of that particular WhatsApp Web session.
Select the three-dot menu icon from WhatsApp’s main window to open it. Select Linked Devices. Examine the logged-in devices.