Me and my neighbour don't speak because of this issue. Her son has behavioural problems. And so does mine (ADHD). I've told my son, that if ANY adult comes across him doing anything he shouldn't while hes playing out and im not there to see it, they absolutely CAN tell him off. It's not just parents and teachers who can discipline children, it's every adults responsibility to stop bad behaviour if they see it, to teach children how to behave acceptably. A couple of times I've had another adult bring my son to the door and explain they've had to tell him off for such-&-such. I have supported them and also reprimanded his behaviour. ADHD children can be more difficult to teach when it comes to discipline and acceptable behaviour, as they can often do things without realising its bad. But that doesn't mean they shouldn't be told off. They need reminding more often of how their behaviour can affect others. My sons bad behaviour when out is thankfully pretty infrequent, because now he's afraid of the consequences. Its made him think more about his own actions.
My neighbour OTOH thinks only she should tell her DC off. Even if she's not around to witness his bad behaviour (which is frequent, and getting worse as he hits puberty) and has blanked me for 4 years because I told her son off once for physically attacking smaller younger children out on the street.
The lack of anybconsequences is why his bad behaviour is so frequent, because nobody is allowed to say a word to him. If they do, she kicks off and sends her husband out to throw his weight around, making threats. This boy is bow becoming such a bully, he even started harassing another severely mentally ill neighbour. I told him off again, so not only am I blanked, I'm actively given dirty looks and they throw old food and litter over our fence.
Before she started blanking me, she told me abouy her own sister cutting her off for the same thing. The sister was so sick of this boys constant bad behaviour in their home, and my neighbour never doing anything about it (but kicking off if the sister told him off), the sister decided they couldnt visit anymore. They had a huge falling out about it and my neighbour was absolutely incensed... "that's MY son, how dare she tell him off!!"
OP, that is your home and everyone who enters it must follow your rules and respect it. If they don't, you have every right to tell them off. How else will they learn not to treat other people and their properties like crap?