Windows Connected Accounts (Office 365 Accounts)
Can be found in the registry if needed:
Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\WorkplaceJoin\JoinInfo\xxxxxxxxxxxx
Computer\HKEY_USERS\xxxxxxxxxxx\Software\Microsoft\Windows NT\CurrentVersion\WorkplaceJoin\JoinInfo\xxxxxxxxxxx
Computer\HKEY_USERS\xxxxxxxxxxx\Software\Microsoft\Windows NT\CurrentVersion\WorkplaceJoin\TenantInfo