If you choose to remove yourself from WhatsApp, here’s what you want to do:
To export your messages, tap the chat you want to save. Tap the name of the chat at the top and scroll down to “Export chat”, then choose whether or not to include media from the chat with it.
Then request your account details by going to “Settings” at the bottom right. Then select “Account” and “Request Account Information”. It will take about three days to receive the data report from WhatsApp, but they will notify you when it is ready.
Finally, to delete your account, go to “Settings”, then “Account” and “Delete my account”. This will delete your message log, remove you from all groups and delete the backup. Now you are free and ready for WhatsApp, and just need to convince friends and family to migrate to another app.