DBdel( ) Deletes a key from the AstDB
DBdel(family/key)
Deletes the key specified by key from the key family named family in the AstDB.
Always returns 0.
exten => 123,1,DBput(test/name=John) ; add name to AstDB
exten => 123,2,DBget(NAME=test/name) ; retrieve name from AstDB
exten => 123,3,DBdel(test/name) ; delete from AstDB