ZyXEL Communications NSA-220 Plus User Manual page 309

In the Certificates manager, select the Authorities tab, select the certificate
3
that you want to remove, and then click Delete.
Figure 162
The next time you go to the web site that issued the public key certificate you just
4
removed, a certification error appears.
Note: There is no confirmation when you delete a certificate authority, so be
absolutely certain that you want to go through with it before clicking the button.
NSA-2401 User's Guide
Opera 9: Certificate manager
Appendix D Importing Certificates
309