What is wrong with this code to remove wp admin bar from one page

You need to remove the (!) infront of the conditional, you can read about PHP-operators here.

Now you simply say that if not on page “image-upload” remove the admin_bar.. Here is the working code:

<?php 
function wpse_80018_hide_admin_bar() {
   // If is on page "image-upload"
   // Remove the admin_bar
   if ( is_page('image-upload') ):
      show_admin_bar(false);
   endif;
}
add_action('wp_head', 'wpse_80018_hide_admin_bar');
?>

Just an example to understand the conditional:

<?php
function wpse_80018_test() {
    // If iam on page "image-upload"
    // Echo honey i'm home!
    // If on another page echo "Working on another page!"
    if ( is_page('image-upload') ) {
       echo "Honey i'm home!";
    } else {
       echo "Working on another page!";
    }
}
add_action('wp_head', 'wpse_80018_test');
?>