Clothes line

Gosh, regardless of any law existing, surely this is trespassing. I would not be happy if someone did it to me. Tying on to your grill is definitely trespassing going on your land, and it will be unsightly. They are trying to dismiss your position. Tell them you insist on it being taken away. You don't know what else they would do if you let them get away with it. Are other householders doing the same? Is there not a street in between you? Forget law, it's your grill not theirs.

Regards 

Pauline 

If you live on a community then you need to speak to the president or administrators about rules. Some places don't allow washing to be hung outside the front of properties. If not I'd speak to the owners politely and tell them not to do it again. They may just be trying it on and if you don't say anything they'll keep doing it.

Just untie the line ??

Have you got a stanley knife or wire cutters?

Your best option would be to contact the President of the building and raise the question with them. Personally I’d think it’s not allowed. Good luck!