Can I switch colors of the phone?

iPhone return policy

If you are not fully satisfied with your iPhone purchase, you can return your undamaged iPhone to the Apple Online Store within 14 days of purchase for a full refund. ... The iPhone must be returned in the original packaging, including any accessories, manuals and documentation.

Depends where you bought it and what their returns policy is. Apple itself offers a 14 day unconditional return policy in the USA and many other countries. Other stores will vary.