Que tal simplesmente
sed -i 's@^\([^{]\+\)\(\.to[^{]\+\)}\s*$@@' your_file
Com Perl (para melhor legibilidade):
perl -pi -e 's@
^ # start of line
( [^{]+ ) # at least one non-{ character (save in $1)
(\.to [^{]+ ) # .to and at least one non-{ (save in $2)
} # that pesky }
\s* # optional white space
$ # end of line
@$1$2@x' your_file