*note before you proceed
If your pool is buried at all you mustn’t lower the water level below the surrounding ground level as you risk a cave in situation.
My suggestion on top of what
@Newdude has already covered is to get the pool de winterized and running before you start draining. Run all the tests so you have some baseline numbers especially cya. This ensures you know you have functional equipment upon refill and can get going with the slam post haste & you can get an idea of what your cya will be after the exchange.
While dealing with the muck while simultaneously draining the pool you’ll want there to be some fc in there. Not necessarily slam level but at least target level.
The draining is fast depending upon your pump - the refill takes a bit longer. I suggest draining from the bottom whilst refilling from the top.
It took me 2+ days with 2 hoses to fill my 25k gallon pool (only fill during daylight hours to avoid the liner shrinking and the weight pulling on the liner & always set a timer to check it)
Get a leaf net (the deep ones with a lip are best for scooping) you can go at it broom & dustpan style with the brush too if you have 2 poles.

If the water gets low enough and you have some waders getting in there may make scooping the muck out easier. (For safety be sure someone is home or can check on you if you wear waders in the pool)
Its gonna be arm day

every day until your scooping is done so come prepared.
There’s no way to avoid the
SLAM Process but a partial drain will help you remove some of the bulk of organic material which should in turn= less liquid chlorine needed overall.
P.S.
if you’re pump is ever inoperable again you can still feed your pool the chlorine it needs daily to keep your pool clear and avoid algae by simply pouring liquid chlorine in slowly (away from the liner) and brushing it around.
The filter only physically removes particulates, while important, it doesn’t provide sanitation which is what keeps algae from proliferating. Keep the fc up, give it a little manual circulation and you’ll be good for a bit until things are going again
Also, the only dumb question is the one you don’t ask- thats what we’re here for! Ask away anytime along your pool journey

Keep us posted on the progress!
Did we mention we love pictures?