It's a dilemma!!

AFAI can tell, with my limited knowledge, this is a tiny, foot high, Sycamore tree. It's never been planted, simply appeared, just over the wall of our garden, in a patch of ground behind our neighbours garage, so that's the dilemma, obviously if left it could grow to a huge height and destroy the concrete panel it's next to, which is part of pur wall, on the other hand I could easily, right now, rip it up, even though legally I aren't entitled. I like it, it's appeared out of nowhere on stony ground, so it's a survivor. Hard to yank it out really, since it may be ten years yet before it reaches the destructive phase. our neighbours don't even know it's there..so what does one do?? Answers on a postcard please<g>