Hi,
Thanks for your inputs.
I have changed the user "admin" (which has "manager" privileges) password through cmd:
2930-F(config)# password manager user-name admin plaintext " "
After applied, I have saved and compare the running and startup-config. They are identical. However, when I do ssh using the admin user, I am getting denied.
It should work as you said I don't need to reboot the switch. Please help.