You can’t change the password for your organizational account in Office 365 because your organization creates and maintains your account. Your organizational account is the user account that is assigned to you by your organization to provide access to Office 365 and other Microsoft cloud services.
If you don’t see a link to change your password on the Password page, your organization doesn’t let you change your password on this site. Your organization might have sent you instructions to help you change your password. Follow those instructions to change your password, or ask your admin for help.