use strict;
my $str = 'GN1RLWFH0546-2020-04-10-18-09-52-563945.txt
JOHN-DOE-2020-04-10-18-09-52-563946t64.txt
DESKTOP-OHK45JO-2020-04-09-02-27-11-451975.txt';
my $regex = qr/-\d{4}-\d{2}-\d{2}.*$/mp;
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