如何关闭所有活动

Login_page>>home_page>>search_account>>delete_account

然后我删除了一个帐户，我想去login_page. 我的意思是关闭所有活动的实际代码是什么login_page？

这是我的代码，但不起作用。

AlertDialog.Builder builder = new AlertDialog.Builder(delete_class.this);
    builder.setTitle("Delete");
    builder.setMessage("Do you want to delete your account ??");
    builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            String id = MainActivity.return_id();
            Firebase firebase = new Firebase("user");
            firebase.child(id).removeValue();
            finish();
            Toast.makeText(delete_class.this,"Account deleted successfully",Toast.LENGTH_LONG).show();
        }
    });
    builder.setNegativeButton("No",null);
    AlertDialog alertDialog = builder.create();
    alertDialog.show();