Deleted WhatsApp chats not gone from the database on your device. Weird the chats in the database are
not encrypted.
Read:
http://www.zdziarski.com/blog/?p=6143Certain restore Apps already able to recover deleted WhatsApp data: FonePaw/Reincubate
If you mean Privacy, do not use WhatsApp.
When you really wanna loose the data uninstall Whatsapp or use a complex back-up password.
Remember in these times and days, never entrust the Internet with private or other info you do not intend to share with the world.
The Internet never forgets and all your data will be there forever and a day.
Know Google and others sits on them info and where it goes no-one knows,
so they even might to come to boomerang and bite you back.
Forewarned is forearmed,
polonus