You can also use PERL API
Sample perl that deletes the TRUSTED host jsdksample-trustedhost
You can use perl API to read in a file list of each trusted one at a time, delete in a loop until EOF
#Initialize the Policy Management API
use Netegrity::PolicyMgtAPI;
$MyTHName = 'jsdksample-trustedhost';
$adminName = 'siteminder';
$adminPwd = '***********';
$policyapi = Netegrity::PolicyMgtAPI->New();
print "Step 1. Log in the admin and create an API session.\n";
$session = $policyapi->CreateSession("$adminName", "$adminPwd");
print "Step 2. Deleting TrustedHost. \n";
$status=($session->DeleteTrustedHost($session->GetTrustedHost("$MyTHName")));
print "$MyTHName \n\n";