Remove lines from file 1 that are in fiel 2

grep -v -x -f f2 f1 should do the trick.

With some explanations:

-v for select non-matching lines
-x for matching whole lines only
-f f2 to get patterns from f2.

sgrep like a player

Used to remove nodes with a given colour from a SVG file

 sgrep -i 'inner("<"..">") not containing ("#00ffff" or "#ff00ff" or "#ff0000")' < survey_plain.svg > survey_really_plain.svg