Which steps should I follow after uninstalling the WhatsAppify app?

No further action is required after uninstalling the WhatsAppify app from your Magento store. Once successfully removed, all associated data and settings will be deleted. You can simply continue using your store as usual. If you decide to use the app again in the future, you can easily reinstall it from the Magento App Store.

You can install Whatsappify from here.