use strict;
my $str = 'Subject_name: English, Teacher_name: John Doe, Remarks: some comment, Overall_marks:87,
Subject_name: Mathematics, Teacher_name: Doe John, Remarks: some comment, Overall_marks:75,
Subject_name: Science, Teacher_name: JD, Remarks: some comment, Overall_marks:80,';
my $regex = qr/Teacher_name:[\w\s]+,\s*Remarks:[\w\s]+,\s*/ip;
my $subst = '';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html