I've read all the comments on this topic but nothing said helps with the problem. I have deleted the contact in question from my contacts and refreshed the Whattsapp chat list several times but the contact doesn't disappear. There are no chats associated with this contact because I've deleted everything related to it.
If you go to Settings > Storage > Apps > WhatsApp
You will be able to clear cache for this app. Hopefully then , it will remove the deleted contact.
Hope this helps.
It cant be done. They will always show even if you delete from contacts, clear chat, delete chat, delete messages. refresh. Nothing works