How to safely and neatly demo a block wall?
This may be a bit overkill, but put a netting on her side of the wall, then climbing on a ladder/scaffolding (which may well be entirely on your property) start hitting the wall from her side through the netting, starting at the top of the wall. The pieces should fall entirely on your property that way. Depending on the netting, you might still get some dust on her property though.

For the dust part, you could offer to temporarily install a dust sheet over her plants. Also, you could probably use/rent a (powered) demo hammer, although using it (from the top) at slight angle from her side may be a little tricky, unlike swinging a sledge hammer. If she gives you access to her property for the scaffolding as well, then using a demo hammer would probably be best. You might be able to regularly demo just from your side using the demo hammer horizontally, but it will take a strong netting to contain all the stuff if you're pushing it into the netting on purpose all the time.

You may be able to do that last bit (demo from your side with a demo hammer) as shown in this vid by just loosening the mortar holding the bricks/blocks together, but it depends on the mortar (strength) and it takes a bit of experience/finesse.