Networks

I configured a cisco router 3845 but i didnt do any configurations for the passwords.Second time i tried to login i had this message :

Cisco Router and Security Device Manager (SDM) is installed on this device.
This feature requires the one-time use of the username "cisco"
with the password "cisco". The default username and password have a privilege level of 15.

Please change these publicly known initial credentials using SDM or the IOS CLI.
Here are the Cisco IOS commands.

username <myuser> privilege 15 secret 0 <mypassword>
no username cisco

Replace <myuser> and <mypassword> with the username and password you want to use.

For more information about SDM please follow the instructions in the QUICK START
GUIDE for your router or go to http://www.cisco.com/go/sdm

Can anybody help me please how to reset the password or access it in order to put a new password for it??