I have been working since I was 18 and plan to stop working at age 62.5. If I stop working and delay receipt of my social security benefit until my full retirement age 66+4 months, will the benefit be decreased as a result of not working until 66+4?
No, your benefit amount won't decrease if you have no earnings from age 62 to 66. Your Social Security retirement benefit rate is based on your highest 35 years of wage-indexed earnings (https://www.ssa.gov/pubs/EN-05-10070.pdf), so if you don't have earnings from age 62+ to 66+ those years simply won't be used in calculating your benefit rate.
On the other hand, if you kept working from age 62+ to 66+ and your earnings in those years were higher than some of your previous highest 35 years of wage adjusted earnings, then your benefit rate would increase. You may want to consider using our maximization software to explore your options and determine your best strategy. The benefit calculator in the software allows you to enter future year projected earnings so that you can gauge precisely what effect working vs. not working would have on your benefit rate.