Moved into a chicken MESS

Background: we recently started renting a house with a big, fenced-in backyard. The owner was the previous tenant. He's a lovely human who LOVES animals, but it's pretty apparent that he's a bit impulsive. He let me know he had chickens but had rehomed them before he moved and said, "I'll leave the coop in case you want chickens". I thought it was very nice of him and maybe, down the line, we would. I've had friends & family that had a few backyard chickens & I know it's more work than I'm capable of right now. I have 3 dogs and was very excited about the back yard, I was ready for some clean up. The owner also said, I did move the greenhouse though." I was disappointed because I plan to put in a garden as well, but no big deal (more on that later). We didn't investigate the backyard as much as we should, because when we went to see it, our area had just had massive amounts of rain & the whole town was dealing with flooding so the backyard was very soggy.

Info gathered after moving in: the greenhouse was part of the chickens winter coop & connected to the main coop. What was left when the greenhouse was moved was chicken waste covered with straw that is 1' or more deep and about 10'x5'. He also explained that his chickens, "got a little out of control and I ended up with about 26." The main coop that is still on the property is A MESS. I don't even want to go in there because there is likely mold & other hazards. I also found the remains of a chicken in the outside shelter (cause of death unknown).

What I'm hoping to find help with: what's the best way to deal with this 10'x5' left over waste pit? My dogs think it's tasty and it is starting to really stink. I could add some of it to a compost pile, but it is way too much for any kitchen garden. Any suggestions on dealing with the coop? I don't want my dogs getting into it and I don't want it to become more of a hazard.

If you read all of this, thank you! And thank you in advance for any help/suggestions.