I was just in another thread, "springtime stink in the run" and there was a link to another thread on the deep litter method. in that link, which I am about to post for your benefit, is a lady who on here goes by 'beekissed' who has done a 9 1/2 minute video explaining how deep litter and cold composting works. This will be good for you to watch being new.
https://www.backyardchickens.com/t/70/deep-litter-method/1660
However, I know that's not what you're asking in this thread, for this thread is about cleaning out your brooder.
A few questions if I may:
how many chicks?
how big is the brooder?
how much pine shavings are you using each fill up?
here's my explanation of how it works, summarized and followed up with how I did my brooder in my kitchen. Had very little smell to it.
Chickens are poop machines! they eat, they drink, they poop. they run around in it, they pick at it, they eat it, they'll pick it off each others behinds. They sleep a little while and then they do it all again. They will even poo when they sleep!
this batch of chicks I started with 8, and wound up with 14 total. I quickly assembled a temporary brooder box, in our Kitchen! I had the guys at home depot cut two sheets of osb board in half, long ways. This gave me 4 pieces that were 2' x 8'. When I got home with them, I cut one of those pieces so that I had 2 pieces that were 2'x2' square. I used those for the ends, and took the other three pieces and made 2 walls and 1 floor. Some quick 1x2 framing inside the corners and along the bottom edges and viola, I had a brooder box! I also framed out some 4 ft by 2ft 1x2 frames and covered them with chicken wire, a couple hinges on each and I had two 'lids'
Ok, theres the box, so what next? 3" of pine shavings. Sprinkle in a couple of cups of sweet pdz. In a few days, there will begin to arise an odor.......add more pine shavings, and mix them up!
How it works: wet poo smells. The dry pine shavings will absorb the wetness from the poo, along with the sweet pdz. Dry poo doesn't have a smell to it. I would do this until I had 6 or 7 inches of bedding in the box, then when it came time for the aroma to begin to arise, I'd get a dust pan and a large garbage can, clean it out, put in a new 3" of pine shavings and take the old out and spread in the garden spot.
If you're wanting to compost this, of course you'll need your compost bins set up and turn it regularly, but that's another thread in and of itself.
Now go watch the video by beekissed, and you'll see the only difference in doing a brooder and a coop and run is the amount of time between total clean outs, if you ever actually do a total clean out on the coop!
hope this helps!