Can I scan one side of a document only?

To scan only the front side (one side) of a document, you will need to change the specific profile settings in ScanSnap Home.

To change the profile settings:

1.  Open the [Edit profiles] window.
   
   
   
2.  Select the profile you want to change.
3.  Select [Simplex] for [Scanning side] in [Scan settings].

For details:
ScanSnap Help
(Select the model name of the ScanSnap at the top of the page)