Open WhatsApp
Go to the chat containing the message
Tap and hold the message you want to delete
Select additional messages if needed
Tap Delete
Choose Delete for me or Delete for everyone
To delete multiple messages, open the chat menu and select Clear chat if needed
To delete an entire chat, open the chat menu and tap Delete chat
To delete all chats, go to Settings
Tap Chats
Tap Chat history
Tap Delete all chats