Case 1: Can't remember your password and wish to reset it
You can do this by first clicking on "Sign in" on the Ahrefs Homepage.
Then click on "Forgot your password".
By submitting your account's email address, you'll receive instructions via email on how to reset your password. Simply follow the instructions and you're good to go! :)
Case 2: You know your password but wish to change it
You can do this within your Ahrefs account by following URL https://ahrefs.com/account/my-account and clicking "Change password":
Key in the old password and the new password, and you're good to go! :)