How do i download and delete data created by an app on the iphone?

Hi PrivateTrustRes,

I'm sorry, I'm a bit unclear what you mean by "download" in this context. As far as deleting the data associated with a specific app in iOS, you may find the information and steps outlined in the following article helpful:

See how much storage you've used on your iPhone, iPad, and iPod touch - Apple Support

Regards,

- Brenden