Add admin user to welcome screen.

Start the Registry Editor Go to:
HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \
Windows NT \ CurrentVersion \ Winlogon \ SpecialAccounts
\ UserList \
Right-click an empty space in the right pane and select New
> DWORD Value Name the new value Administrator. Doubleclick
this new value, and enter 1 as it's Value data. Close
the registry editor and restart.
*Note:Note down previous value for precaution.