What i think is that you should keep an open mind about window cleaning.To even think about moving away from it is the most stupid thing i ever heard from you.The renting won't work, and the selling won't get you what your business is worth.
You do not have any option at all but to employ.You have just got to make the best fist of it that you can.You've built a good business, carry on doing that- it's what you are good at, your niche, so carry on.
To carry on you do need a open mind though.Have a look at your options, business, franchises, whatever, and then look freshly at wc.
We are all good at some bits of the job and worse at others, you need to get out of your comfort zone and work on the bits you don't like, such as employing.You will earn less than you do now initialy, accept that and don't let it stop you.