How do I delete app purchases

you cannot delete app purchase history... but you can hide stuff

Hide App Store purchases - Apple Support

or if you were just asking how to delete stuff from your device..

How to delete apps on your iPhone, iPad, and iPod touch - Apple Support

You don’t delete an app purchase. You can’t turn back time. What exactly are you wanting to do? Request a refund?

Request a refund for apps or content that you bought from Apple - Apple Support