Deleting a line

[hearn]

Now that I've got my .htpasswd file adding entries, I need to know how to delete entries. I have no idea where to begin on this one. How would I search for a username and password within a .htpasswd file, and then delete that line of the file and move all entries below that one up by one line? If someone can post some code for it I'd be VERY grateful. Thanks for your time and thanks in advance!

[hand]

htaccess

user3:$apr1$tT0.....$n3bvYfxDUxu.2mWX2ELUh/
user2:$apr1$uU0.....$mjPHRwxg3.MNMyXzUDyh5/

<?php
$file = "htaccess";
$userToDelete = "user2";

@$fp = fopen($file,"r"); 
if (!$fp) {
    print "File $file doesn't exist<br>\n";
} else {
    $fileok = "ok";
    while (!feof($fp)) { 
        $lines[] = fgets($fp, 4096);
    }
}
@fclose($fp);
if ($fileok == "ok") {
    $fp = fopen($file,"w");
    for ($i=0;$i<sizeof($lines);$i++) { 
        $check = explode(":",$lines[$i]);
		print "<br>reading user <i>$check[0]</i> ";
        if ($check[0] == $userToDelete) {
			print "user <i>$userToDelete</i> deleted";
		} else {
	        fputs($fp, $lines[$i]);
		}
    }
    fclose($fp);    

}
?>