Seperate /user/register fields and admin/people/create i extended the add user field by adding a role field as part of the fields that will be displayed when you click  create user in mydomain.com/user/register. With the addition of some rules, this helps me to assign automatic roles to registering users.

I however noticed that when you  add user from the admin menu in People>Add user, this roles fields are added to the already existing fields. This is undesirable because the Add user page already have a section where you can pick the role. This therefore makes the form to have 2 different section where you can pick roles.

I want to hide my custom role field in mydomain.com/admin/people/create but show it in mydomain.com/user/register. Please how do I achieve this
Probably hook_form_FORM_ID_alter on user_register_form then some logic like 

function MYMODULE_form_user_register_form_alter(&amp;$form, &amp;$form_state) {

  // Is logged in user admin.
  if (user_access('administer users')) {

    // Hide myfield.
    $form['myfield']['#access'] = FALSE;
  }
}