1
The account on the security tab on the properties dialog of that shortcut named 'account unknown 'S-1-15....' is not a user account it is a security descriptor used by Windows, do not try to remove that account.
2
Do you have a Nikon camera that you connect to your PC, the 'wireless transmitter utility' process is known to be associated to a Nikon app.
If you do not connect a Nikon camera, right click that shortcut and select properties.
Select the details tab on the resulting Properties dialog box.
Please provide a screenshot of that Details tab.