I would drain half and refill. Also, add your pool info to your signature, more here about what to put in your signature and how to do it, Pool School - Read This BEFORE You Post
Even if you did drain your whole pool and refill, your water balance over the last few years have destroyed your liner. You drain it and you'll watch that liner pull away from the wall, shrink before your very eyes and once you try to fill it, you'll collapse the pool walls trying to get a shrunk liner to hang. And even if you are successful, you'll still have algae and bacteria in the pool and still need to SLAM.
Your education here at TFP is just as important as us wanting you to have a pleasurable experience in a TFP pool. But until you dive into the information and start digesting it, you will have a huge road block that will not only frustrate the endless help and wealth of knowledgeable people here, it will frustrate YOU!
You can not SLAM without a reliable test kit. Until you get one, you will waste your time, our time, your money and your summer.
People will use a garden hose to siphon above ground pools. Put on end in the pool first then push the rest of the hose down and into the pool filling it with water. Once the whole thing is in the pool, cover one end and take it out then quickly lower it to the ground as you uncover the end. This should create enough vacuum to siphon the water out pretty efficiently. And you can move the hose around the yard and water whatever you want to. I don't see any reason this couldn't be done with your vacuum hose either. One note, the end that stays in the pool might have to be weighed down so it stays near the bottom.
Here's an example Mom siphoning pool water 101 - YouTube