Done a few of these.
Dig around, hack the roots with a good axe.
Assorted stump waggles.
You usually get to a point that the stump can be a lever.

Dont use your "best" spade...you will be tempted to
apply to much pressure at some point, when adrenaline and frustration get
the better of you....

Like I sya axe, waggle, patience