Open WhatsApp
Go to the chat with the contact
Tap the contact name at the top
Tap Edit or the three-dot menu
Select View in address book or Edit contact
Delete the contact number from your phone contacts
Save the changes
Refresh WhatsApp contacts
On Android, go to WhatsApp Settings
Tap Chats
Tap Chat history if needed
Delete the chat if you want to remove the conversation too
On iPhone, open the Contacts app
Find the contact
Tap Edit
Tap Delete Contact
Confirm the deletion
Restart WhatsApp if the contact still appears