Nerlens Noel
TMZ Sports broke the story ... the 76ers star was sued for more than $40,000 by the property owners who say the 22-year-old trashed the place so bad, the place looked like a bomb went off inside.
Among the accusations ... carpet destruction, toilets clogged with cotton balls and feces, water damage, broken appliances and allegations he left a tombstone on the front step as a death threat.
Now, Noel has finally fired back in legal docs of his own -- adamantly denying he went "Project X" on the place.