If you refer to extensions, the way to do it is:
First: once having the Dn (or extension), find the TN (Physical location):
LD 20
Req Prt
Type DNB
Dn xxxx (write down the Dn and you will get the TN)
Second: Once you have tne TN you can erase it
LD 20
Req Out
Type zzzz (you must know if it is a 2616, 2008, 500, etc)
Tn xxxx