Where to sign in to Office 365 for business
Sign in at: www.office.com/signin
Sign in at: login.partner.microsoftonline.cn
Sign in at: portal.office.de
Switch between accounts
If you're already signed in with one account, for example, you're signed in with a Microsoft account and you want to sign in with a work or school account instead, or vice versa, do the following:
Sign out of the account you're signed in with, and then sign in with the new account. Or,
Open a private browsing session in a new browser window. Search your web browser's help if you're not sure how to do this.
What if my password doesn't work or I still can’t sign in?
See I can't remember the account or password I use with Office and select the tab for your Office product.