Only the state of Pennsylvania currently requires a Power of Attorney form in which the Attorney-in-Fact must sign the document.
A Power of Attorney is created under the assumption that the person being named to handle matters for another is willing to accept the responsibility.
If that person is not willing, then they should not be listed as the Attorney-in-Fact.
If Power of Attorney is granted by signature and the Attorney-in-Fact named declines the appointment, the Attorney-in-Fact may make such a declaration in response in writing, or the person who created the document can simply destroy said document to end the process.
To create a Power of Attorney document quickly and easily, see this page.