Let's say you filed for Social Security at the age of 62, and you're kicking yourself for not waiting longer for the higher benefit. No biggie. Believe it or not, you actually have a second chance. You can simply file Social Security Form 521, and request the withdrawal of your application.
By submitting this form, you're essentially coming out of retirement. Of course, there's a catch: You'll have to pay back all the Social Security benefits you've received thus far.