how i can delete whatsapp documents and data

JimmyCMPIT's advise on deleting the app to delete it's associated documents and data holds true for other apps as well, unless they contain a means within the app itself for doing it. AFAIK, iOS doesn't allow you to delete only the documents and data of an app.

delete the App

How to delete apps on your iPhone, iPad, and iPod touch - Apple Support

Yes! You can delete the data of whatsapp on your iPhone.

There are two ways for doing that -

1) Go Whatsapp. Then choose settings and then you need to select Chats. You need to simply scroll down at the bottom of the chats. There you’ll see the clear chat options.

Whatsapp > Settings > Chats > Clear All Chats or Delete All Chats

2) Choose any person or a group whose data & documents you want to delete. Click on his profile. Scroll down to bottom. There’ll see that Clear Chat option.

Yes, you can delete data and media from within the app, selecting chat by chat.

Go to Contact WhatsApp

They will help you.

Regards

Giulio

see this link

WhatsApp FAQ - Restoring your chat history

if your question is answered you should contact the developers of Whatsapp for clarity on their product.

You're welcome

This also helped me a lot. Thanks 👌-1F3FB;