Hey,
Go to the debug mode and delete the file.
NS_CSS_Backup# llama
NS_CSS_Backup(debug)# ap_file delete c:/Core/
After this give the name of the file..
If needed put a ? after each parameter. For eg
NS_CSS_Backup(debug)# ap_file delete c:/C?
Core APR 12 22:51:38
512 CertStore AUG 17 18:01:20
512Cheers!!
Sagar