Some maples will stump sprout or sucker pretty badly. I'd take about half
of the maple's mass out now and then girdle the main trunk as low as possible.
Let the maple continue for a few more years... it'll get weaker and weaker
because it can't translocate photosynthate to the roots (you've stopped
the phloem pathway by girdling), thus starving out the roots. Go ahead and
take a little more out of the top of the tree each year it survives -- you
don't want to initiate suckers by just whacking down the whole tree at once.
When it puts out only a feeble set of leaves in the spring, it's time to
finish the maple removal.

Kay