I’ve read different suggestions on removing the grass with the sod remover vs. not removing the grass under the pool and I’ve also read use the sand as a base and also been advised not to use and what is the best? Thank you in advance.
Much of what you are asking is location dependent based on soil conditions, amount of rainfall, etc. I'd say that for most AGP owners, they prep the ground by removing the grass/weeds. They do this to ensure nothing will try to grow up & through the liner later. It also allows them to clear-out any sharp rocks or twigs that may be hidden in the soil or grass because once the pool is filled, you're stuck. Prepping the ground also allows you to do the very first (most important) thing and that is leveling. An AGP must be level - we recommend to within one inch all around.
Once that's done, the choice of base material under the liner is again personal preference and/or based on the location. Sand is easy to level and soft to the feet, but does not protect the liner from growth underneath and can also get washed-away if heavy rains flow towards the base of the pool. So those who use sand make sure to have a barrier around the base of the pool or build-up the area so water goes way from the sand. Others chose insulation-type pads under their pool for their durability and protection.
So you have options. Now it's just a matter of deciding what works best for you. Do searches in the AGP sub-forum and you'll see lots of examples. Hope that helps.