dw.
I have two rental houses with pools... Thankfully they are somewhat near me, so I can take care of both of them. Unless you can find a renter with a real interest in maintaining a pool, you will be lucky if they even remember to add water...
I only see two options...
1. Write the whole pool off and take it out.. The cons are the loss of the investment into the pool. The pros are you are done with it and there is no additional costs.
2. Hire a pool service while you are gone forever. The pros are that you have a pool.. The cons are that you have to pay for a pool service a monthly fee, and then an opening fee and a closing fee, and fees to repair things and the cost for all the equipment that will go bad while you are gone. And of course a new liner when you get back..
Your experience may differ, but I would never rent out a house with a pool unless I was sure that I was returning in 2 years of less, and even if I did that, I would plan on setting aside a good chunk of the rent for future maintenance and repairs.
Just think about it for minute... The majority of home owners don't do a very good job of maintaining their pools and they own them!! What do you think most renters will do..
And to be honest, the pool is not the only thing you have to be thinking about. I am very lucky in the fact that my dad could fix anything and he taught me how to fix "almost" anything..

I would not have any rental properties if I could not be the local property manager... I can generally fix most things that go wrong and when I can't I can get the right people to get the job done.
If you can't be in the local area, then you will need a property manager who will take 10% off the top and then take more money whenever something goes wrong and his crew or subs needs to go out and fix something. A simple jammed garbage disposal that can be fixed with an allen wrench, will turn into a new garbage disposal pretty quickly.
Not trying to be a downer, but renting a property needs to be fully thought out before doing it.
Thanks,
Jim R.