I've found that a sawzall 10-12" out from the rootball works amazingly well at getting these out of the ground. The only ones I've lost were because I flat-cut the bottoms while misjudging how many feeder roots were left. (I was aggressive because I had too many of these already.)
With this one so small, a sawzall may not be necessary. I would wait to chop it until after you've got it out of the ground in case you need the leverage.