If you're referring to your ingame account, on the main site,
www.animusro.com, there is a Character Infobox to the left. Put in your account details, and then a button to change your password will appear.
As for your forum account, you can change it when you click on "Profile", and then "Modify Profile -> Account Settings".
In case you forgot your ingame password, but still have access to the email it is registered to, you can either submit a support ticket, or send me a forum PM with your account name, and I will send the password to your email.
