How to delete a secret gnuPG key using a php script ?

[Graziano]

Hello,

I am able to delete gnupg key from ssh.
Now I am trying to do that from a php script.

I am trying this to delete a secret key

<?
exec("/usr/bin/gpg gpg --no-secmem-warning --home /test/.gnupg  --batch --yes 
--delete-secret-key B209E218");
?>

But I receive this error 
gpg: Warning: using insecure memory! usage: gpg [options] [filename]
The key dir is located here  /home/test/.gnupg


Any idea ? Thank you