(PHP 4, PHP 5, PHP 7)
imap_delete — Mark a message for deletion from current mailbox
$imap_stream
   , int $msg_number
   [, int $options = 0
  ] )
   Marks messages listed in msg_number for deletion.
   Messages marked for deletion will stay in the mailbox until either
   imap_expunge() is called or
   imap_close() is called with the optional parameter
   CL_EXPUNGE.
  
imap_streamAn IMAP stream returned by imap_open().
msg_numberThe message number
options
       You can set the FT_UID which tells the function
       to treat the msg_number argument as an
       UID.
      
   Returns TRUE.
  
Example #1 imap_delete() example
<?php
$mbox = imap_open("{imap.example.org}INBOX", "username", "password")
    or die("Can't connect: " . imap_last_error());
$check = imap_mailboxmsginfo($mbox);
echo "Messages before delete: " . $check->Nmsgs . "<br />\n";
imap_delete($mbox, 1);
$check = imap_mailboxmsginfo($mbox);
echo "Messages after  delete: " . $check->Nmsgs . "<br />\n";
imap_expunge($mbox);
$check = imap_mailboxmsginfo($mbox);
echo "Messages after expunge: " . $check->Nmsgs . "<br />\n";
imap_close($mbox);
?>
Note:
IMAP mailboxes may not have their message flags saved between connections, so imap_expunge() should be called during the same connection in order to guarantee that messages marked for deletion will actually be purged.