Removing elements for non-admin users
Are they in the administrators group? Since then you might be able to do something like (untested):

CRM.api3('GroupContact', 'get', {
  "contact_id": "user_contact_id", // use this exact string to mean current user
  "group_id": "Administrators"
}).then(function(result) {
  if (result.count == 0) {
    // Not in the admin group
    // ** do your removal stuff here **
  }
});


There is also CRM.checkPerm() to check a CMS permission. See e.g. https://github.com/civicrm/civicrm-core/blob/5.18.4/templates/CRM/Tag/Page/Tag.tpl#L123, e.g. CRM.checkPerm('administer reserved tags')

if (!CRM.checkPerm("administer CiviCRM")) {
  // do your removal stuff
}