You must completely sever the pup from the parent plant, and they pry and wiggle it till it comes loose from the soil. Depending on the amount of roots it has, that may be easy or hard.

Here is any idea of the tool you should use to minimize the disturbance of the parent plant's roots. http://www.acehardware.com/sm-collins-axe-tamper-digging-bar-db16--pi-1274440.html Here is another. http://www.amazon.com/72-4-PH-Digging-Bar/dp/B000A1CKC0