Q: how can i delete all my whatsapp chats ho

Hello there, aya_yf.

It sounds like you may be wanting to delete the chats that are saved by your Whatsapp app. One way to remove all app related data is by deleting the app itself. The steps for doing so are outlined here:

Delete music, movies, podcasts, and other content from your iPhone, iPad, iPod touch - Apple Support

      

Delete an app

Remove an app using the steps below:

1. Tap and hold on the app until it jiggles.
2. Tap the X in the upper-left corner to delete.
   You might be asked to confirm that you want to delete the app. If you see a pop-up that says, "Deleting [app name] will also delete all of its data," tap Delete.

If there is an alternate setting available to prevent chat data from being saved, without deleting your app, then contacting the Whatsapp developers may be a good next step:

If an app you installed unexpectedly quits, stops responding, or won’t open - Apple Support

Contact the app developer

If you see this issue again, contact the app developer for help:

1. Find the app in the App Store.
2. Tap the app, then tap Reviews.
3. Underneath App Store Customer Reviews, tap App Support.
   

Thanks for being a part of Apple Support Communities.

Cheers.