I've never bothered to make this easy.
If you installed in /usr/local (the default) then you type either:
$ su
password:
$ rm -rf /usr/local/bin/{fontforge,sfddiff} \
/usr/local/lib/{libgdraw,libgunicode,libuninameslist}* \
/usr/local/lib/pkgconfig/fontforge.pc \
/usr/local/man/man1/{fontforge,sfddiff}.1 \
/usr/local/share/doc/fontforge \
/usr/local/share/locale/*/LC_MESSAGES/FontForge.mo
or if you are on a mac:
$ sudo rm -rf /usr/local/bin/{fontforge,sfddiff} \
/usr/local/lib/{libgdraw,libgunicode,libuninameslist}* \
/usr/local/lib/pkgconfig/fontforge.pc \
/usr/local/man/man1/{fontforge,sfddiff}.1 \
/usr/local/share/doc/fontforge \
/usr/local/share/locale/*/LC_MESSAGES/FontForge.mo
password:
If you've installed to a different prefix (/usr perhaps) then simply substitute /usr for /usr/local above.