If you've forgotten your CRM password, you can follow these instructions for resetting.
If you know your password but want to reset it, from within your CRM go to Manage Your Account:
Then, click Manage Database Users & Teams in the Admin section:
From this page, locate your name in the Current Database Users section, click your Actions menu and then select Change Password:
You would then see the below:
Then, it's just a matter of typing in your current password (in the "Your Current Password" field), new password, confirming the new password and clicking Save.
Note: You must be an admin user of the database in order to have access to the Manage Database Users & Teams page. If you are not, you would need to reset using the reset method described here.