<p>On a PLA print where stringing has occurred, what is the best way to remove it during post processing?</p>
<p>Should I simply cut it with a hobby knife and sand the surface or are the better techniques to use?</p>

Use a hobby knife with a chisel blade (straight edge perpendicular to handle, beveled on one side only).
Apply with beveled edge against workpiece. Raise the handle in small increments while stroking over the flaw until it is entirely removed.  This provides pretty good control to prevent gouging.
Avoid sanding.
This method also works well for removing "ribs" caused by gaps in painter tape applied to print bed.