You can find multiple questions/answers to this problem in this site... One of the most recommeded approach is using hook_form_alter
hook: example:
function MY_MODULE_OR_THEME_form_alter(&$form, &$form_state, $form_id) {
// dpm($form);
// dpm($form_id);
if($form_id == 'MY_NODE_FORM_ID') {
$form['#after_build'][] = 'custom_my_node_form_after_build';
}
}
function custom_my_node_form_after_build($form) {
// dpm($form);
// Find the right field's format option with dpm() function
$form['MY_FIELD']['und']['0']['format']['#access'] = FALSE;
return $form;
}