Chrome:
Settings > Show advanced settings > Content settings > All cookies and site data.. > Search for office365.com > Click “Remove all shown”

Firefox
Select Options > Privacy >  Click “remove individual cookies.” > Search for office.365.com > Click Remove All

Internet Explorer
Select Internet Options > Click Settings under the General tab > Click View files >Search for and delete any cookies from office365.com > back in IE Navigate to the Caches and databases tab > Select office365.com and click Delete