How to revoke superuser after user has enabled it?

[nex7er]

I have a switch where, when isChecked is called the app requests superuser the normal way. I however want to also add the ability to disable root when the switch is toggled back to off. How can I do this?

My Switch's onCheckedChanged:

if (isChecked) {
                    edit_status.putBoolean("rootEnabled", true).commit();
                    edit_status.putInt("customVisible", 1);

                    Process p;
                    try {
                        p = Runtime.getRuntime().exec("su");
                        DataOutputStream os = new DataOutputStream(p.getOutputStream());
                        os.writeBytes("exit\n");
                        os.flush();
                    } catch (IOException e) {
                        // TODO Code to run in input/output exception

                    }

                sensitivity_layout.setVisibility(View.VISIBLE);


                } else {
                    edit_status.putBoolean("rootEnabled", false).commit();
                    edit_status.putInt("customVisible", 0);
                    sensitivity_layout.setVisibility(View.INVISIBLE);

                }