When a person died on a corner of the intersection, or in the middle of the sidewalk ... it is always tragic. Then people brought flowers, dolls, notes and stuff to the particular area to memorialize.
Nice, but that is crossing the boundary. Hello, people lives around here, you do not.
I had a friend whose his parents owned the property which someone rode the 4-wheeler motorbike and got killed on their property -- they felt awkward seeing the dolls, flowers and notes on their property.
To take it off will make them furious -- but it is their property, their home -- go and memorialize him somewhere in the garbage dumpster, please.