diff --git a/ACU/Trace.pm b/ACU/Trace.pm
index 2cf448b..fba6621 100644
--- a/ACU/Trace.pm
+++ b/ACU/Trace.pm
@@ -115,6 +115,14 @@ sub addId($$;$)
     $self->{ids}{$key} = $value;
 }
 
+sub delId($$)
+{
+    my $self = shift;
+    my $key = shift;
+
+    delete $self->{ids}{$key};
+}
+
 sub toString ($;$)
 {
     my $self = shift;
diff --git a/commands/grades/send_bonusmalus.pl b/commands/grades/send_bonusmalus.pl
index 8b7e1e3..f618d5a 100644
--- a/commands/grades/send_bonusmalus.pl
+++ b/commands/grades/send_bonusmalus.pl
@@ -45,5 +45,6 @@ if ($#ARGV >= 1)
 }
 else
 {
-    say "$0 <project_id> [project_year] <file> [files ...]";
+    say "$0 [-d] <project_id> [project_year] <file> [files ...]";
+    say "\t-d: delete bonus for listed logins (matching value if given)"
 }
diff --git a/process/files/intradata_get.pl b/process/files/intradata_get.pl
index 9c6890c..fdde9b0 100644
--- a/process/files/intradata_get.pl
+++ b/process/files/intradata_get.pl
@@ -151,6 +151,7 @@ sub grades_new_bonus
     my $args = shift;
 
     my $project_id = $args->{param}{id};
+    my $delete = $args->{param}{delete} // 0;
     my $year = $args->{param}{year} // LDAP::get_year;
 
     if (! $project_id) {
@@ -177,7 +178,9 @@ sub grades_new_bonus
 	log TRACE, $args->{files}{$kfile};
 	log TRACE, @lines;
 
-	my $value = 1;
+	my $value;
+	$value = 1 if (!$delete);
+
 	# Looking for a global value 
 	if ($lines[0] =~ /^(\d+)$/) {
 	    $value = $1;
@@ -193,7 +196,11 @@ sub grades_new_bonus
 		my $tvalue = $2 // $value;
 		my $trace;
 
-		log DEBUG, "Applying bonus for $login:$tvalue";
+		if ($delete) {
+		    log DEBUG, "Deleting bonus for $login";
+		} else {
+		    log DEBUG, "Applying bonus for $login:$tvalue";
+		}
 
 		if (-e "$basedir/$year/$project_id/traces/bonus/$login.xml") {
 		    open my $xml, "<", "$basedir/$year/$project_id/traces/bonus/$login.xml" or croak $!;
@@ -201,17 +208,28 @@ sub grades_new_bonus
 		    $trace = Trace->new($xml);
 		    close $xml;
 		}
+		elsif ($delete) {
+		    next;
+		}
 		else {
 		    $trace = Trace->new();
 		}
 
-		$trace->addId($kbonus, $tvalue);
+		if ($delete) {
+		    if ($tvalue && $tvalue == $trace->getIds($kbonus)) {
+			$trace->delId($kbonus);
+		    } else {
+			$trace->delId($kbonus);
+		    }
+		} else {
+		    $trace->addId($kbonus, $tvalue);
+		}
 
 		log DEBUG, "Updating $basedir/$year/$project_id/traces/bonus/$login.xml";
 
 		open my $xml, ">", "$basedir/$year/$project_id/traces/bonus/$login.xml" or croak $!;
 		print $xml $trace->toString();
-		close $xml
+		close $xml;
 	    }
 	    else {
 		log WARN, "Invalid login $line, line skiped";
diff --git a/process/projects/gen_grading.pl b/process/projects/gen_grading.pl
index dacdaeb..6c04c57 100644
--- a/process/projects/gen_grading.pl
+++ b/process/projects/gen_grading.pl
@@ -56,7 +56,7 @@ sub process
 
 	my @keys = keys %$ids;
 	my $def_i = $keys[0];
-	$def_i =~ s/^(.+)g.*$/\1/;
+	$def_i =~ s/^(.+)g.*$/$1/;
 
 	$ids->{$def_i.'_end_$LOGIN'} = undef;
 	$ids->{$def_i.'_end_group'} = undef;