The Office 365 admin password can be reset at any time from the Winhost Control Panel by clicking Office 365 > Manage (for the applicable subscription).
The Reset Password link will be found next to the primary admin user.
You will be prompted to enter a New Password. Please note that the password must be longer than 7 characters and combine at least three of the following: upper case letters, lower case letters, numbers and symbols.
Click Update and use the new password to log into the Office 365 portal at https://portal.office.com. Because the portal will consider it a first login, you will be prompted to update the password once more by the Office 365 Portal.