public static void MetaExternalUserListRemove(this FolderModel folder, string email, string metadataKeyLocation)
{
var externalUsers = folder.MetaExternalUserListRead(metadataKeyLocation);
externalUsers.RemoveAll(r => r.Email.ToLower() == email.ToLower());
folder.MetaExternalUserListWrite(externalUsers, metadataKeyLocation);
}