Q: How to return an App?

All sales are final.

You cannot - as clearly stated in the terms of use for the iTunes store and the App store, all sales are final.

That is pretty standard for all downloaded software, since nobody has any way to know you have deleted all copies of it if they give you a refund.  There really is nothing for you to "return" in actual exchange for your money back.

If you feel the App was sold to you under misleading representation of what it was or what it did, you can contact Apple and see about an exception to the no refund rule.

http://www.apple.com/support/itunes/contact/

This is nothing new.  Most already know this.

Most places do not allow the return of software.

No company has allowed "returns" on downloaded for-fee software, ever.  Nor has any company I know of ever allowed return of software on DVD, CD, disk or any other media once the packaging has been opened, and for the same reasons.

Perhaps your have never purchased software before, but nothing about such a policy is new, novel nor unique to Apple.