To delete messages received on WhatsApp, you need to perform these steps: open the application, tap "Settings", "Chat", "Chat history" and "Delete all chats". At this point you can return to the main screen.
Steps
Method 1 of 3: iOS
Step 1. Open WhatsApp
Step 2. Tap Settings
It is located at the bottom right.
Step 3. Tap Chat
Step 4. Tap Clear All Chats
This will remove the messages contained in all conversations on the device.
Use this option to keep your chat history and only delete messages, so they don't take up too much memory
Step 5. Tap Settings in the top left
At this point you will have deleted the messages from the device.
Method 2 of 3: Android
Step 1. Open WhatsApp
Step 2. Tap ⋮
It is located at the top right.
Step 3. Tap Settings
Step 4. Tap Chat
Step 5. Tap Chat History
Step 6. Tap Clear All Chats to remove messages contained in all device conversations
Select this option if you want to keep your chat history and only delete messages, so they don't take up too much memory space
Step 7. Tap the ← key
It is located in the upper left. At this point you will have deleted all WhatsApp messages from your Android device.
Method 3 of 3: Desktop
Step 1. Open WhatsApp
Step 2. Click on a chat
Step 3. Click on the v button
It is located at the top right.
Step 4. Click Clear Messages to remove the messages contained in the selected conversation
Step 5. Click Clear Chat to remove the selected conversation's messages from your computer
Step 6. Click Done
At this point you will have deleted all the messages of the conversation.