Scenario

You open SharePoint Designer and load a site from a tenancy for the first time, you are prompted for credentials and the site opens. SharePoint Designer caches those credentials so that you’re not promted to enter them again.

You now wish to open the site again in SharePoint Designer using different credentials, but when you attempt to add another service using the new credentials, you receive the error below during the login phase.

Sorry, another account from your organization is already signed in on this computer…

Solution

To clear the cached credentials follow this procedure (see https://support.microsoft.com/en-gb/kb/2750229)

1. Edit the registry to remove cached credentials. To do this, follow these steps:
   1. Click Start, click Run, type regedit, and then click OK.
   2. In Registry Editor, locate the following registry subkey:
      HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Common\Identity\Identities
   3. Select the Office account that you want to delete, and then click Delete.
   4. In the Identity subkey, locate Profiles, right-click the same Office account that you deleted in step 3 of this procedure, and then click Delete.
   5. Exit Registry Editor.
2. Remove the cached credentials in Credentials Manager. To do this, follow these steps:
   1. Open Control Panel, and then click Credentials Manager.
   2. Under Generic Credentials, locate the account that you want to remove, and then click Remove.
3. Log off, and then log on to the computer.