To remove a bookmark by title in an existing document.

$doc = new PDFDoc($filename);

// how to find and delete a bookmark by title text.
$foo = $doc->GetFirstBookmark()->Find("foo");
if ($foo->IsValid()) {
	$foo->Delete();
}

Read, add, edit PDF outlines and bookmarks Full code sample which illustrates how to read and edit existing outline items and create new bookmarks using the high-level API

The Bookmarks class also allows you to quickly find Bookmarks based on the title text. For example, the above code snippet looks for a Bookmark called foo and then removes it from the outline tree.