"on my own I have been taking 1 baby aspirin every day for almost 3 years. How do I safely cut back. I am 69, female. I really haven't had a exam in many years. I have hiatal hernia. Blood pressure normal to low.

See a doctor. The best thing to do would be to see a primary care provider. There many issues going on that you're managing yourself, and as you get older don't be afraid to have a healthcare professional take a look. Don't forget you are always still in control, but may get some really good advice that you otherwise would get.
First. First let me address the fact that you have not had an exam in many years. You need a physical exam and routine screening (pap, mammogram, bone density testing, colon cancer screening etc.). As far is the Aspirin is concerned. It is good for heart health however it can cause bleeding and worsen some conditions (i.e.Ulcers). You should start to wean off now and ask your doctor if it is recommended to continue. Start taking one every other day for a few weeks then down to twice a week, by then you can be advised by your doctor on how you should proceed. Take care.