PyQt5如何在单击QMessageBox上的“OK”按钮时销毁最后一个小部件

I have a QMainWindow that have a button, when clicked this button, another widget pops up. This widget have a button, when clicked this button an alert message pops up. When I press 'OK' on that message button, only QMessageBox is closing, small widget is still open. I want to close that widget when I press 'OK' on that message button. I couldn't figure out how can I do this. Here is my code;I have a QMainWindow that have a button, when c