Should I sell rental properties

[RaKell Adams]

I have two rental properties which I bought 4 years ago.  My initial investment in each home was $40,000.  Our market has gone crazy, and at this point, if I sold, I would net around $150,000 on each house after taxes and expenses.  

I am currently cash flowing around $500 a month on each home.  I am wondering if I should sell now that I have so much more money invested and am actually getting a much lower return on the total investment. 

I would use the money to pay off my current home where my payment is $1400 a month for principal and interest.  

With our mortgage paid off my husband and I would then be able to retire at age 55 because we also have a solid military pension in place.  

I do not want o buy any more rentals at this point, so exchange the property or reinvesting is not an option.

Please let me know your thoughts.