It pretty much depends on a number of things like, identification, location, size, and condition. To go through all the considerations and possible methods would take more time than I have, but in practice it's all done relatively quickly and a plan of attack worked out.
Basically because all these old bombs are now heavily corroded and sometimes physically damaged, the most common way, if it can't be destroyed on site, is for it to be remotely trepanned and steamed out (sometimes solvents can be used), in situ if possible, sometimes they are burnt but the risk of detonation is still quite high if the fuses are intact. My info is 30+ years old but I'd say it's still applicable.