With difficulty - if the roots are under a solid object like a garage, you can't dig it out. If all the growth is coming off one stem or trunk at the base, you're in luck, because you can sever it at the base and drill or cut into the trunk/stem and apply SBK, a brushwood/stump killer, cover it and leave it to die. If, though, its got several stems coming from below ground level, you'll need to cut each one down, make cuts into the woody stems and apply SBK to each one and cover each one. And check for regrowth in a few weeks and again next year.

SBK is like water though - I suggest to use it neat, wearing gloves, but don't get any on the ground or any surrounding plants.

that's what I'd do to bamboo.
my OH on the other hand would can dig around it then could chop at it with an axe until he had sweated a bit. then he'd treat with sbk. [that's my man for you!]

Well, its good exercise I suppose!