If I want to omit the fingering instructions for some part of a score or the entire thing, I put "\omit Fingering" in the appopriate place. However, it results in warnings ("programming error: Infinity or NaN encountered") if "\set fingeringOrientations = #'(left)" has been previously done. The PDF output is still correct though.
Test case:
\version "2.19.47"
\relative c' {
\clef treble
\key d \major
\set fingeringOrientations = #'(left)
<fis,-1 a-2 d-5>2 <a-1 e'-5>4 d |
\omit Fingering
<a-1 cis-2 fis-4>8 g' g4 cis,2 |
}