Destroy and rebuild object on button clicked in Qt - qt

Question

This is a basic example that I need to get to work to use it in my project.
I need someone to help to destroy and rebuild an object on a button click. What I mean is:
//mainwindow.cpp
{//constructor
ui->setupUi(this);
/*private*/frame = new QFrame(ui->centralWidget);
/*private*/temp = new QPushButton(frame);
QPushButton ok = new QPushButton(ui->centralWidget);
ok->setGeometry(100,100,50,50);
connect(ok, SIGNAL(clicked()), SLOT(des()));
}
{//slot des()
temp->~QPuhsButton();
temp = new QPushButton(frame);
}
See, all I need is temp to be destroyed and rebuilt.
The line temp = new QPushButton(frame); is not working because with or without it, temp disappears from the layout, meaning temp->~QPuhsButton(); is working.
Now, the reason this is bothering me is because this works:
{//constructor
ui->setupUi(this);
frame = new QFrame(ui->centralWidget);
temp = new QPushButton(frame);
temp->~QPuhsButton();
temp = new QPushButton(frame);
/*QPushButton ok = new QPushButton(ui->centralWidget);
ok->setGeometry(100,100,50,50);
connect(ok, SIGNAL(clicked()), SLOT(des()));*/
}
I tried this last piece of code to see if it was possible to destroy and rebuild the object the way I was trying to with a button being clicked. Turns out it is, this time temp = new QPushButton(frame); is working and the button stays there.
EDIT:
thanks for the answer and the comment, but I am sorry because I didn´t realize something before asking the question.
The buttons were being deleted/destroyed, they were just not being "repainted" inside the frame when I write temp = new QPushButton(frame); again, actually they still are not. Help regarding this new problem and again sorry.

Answer 1

Don't manually call destructors, unless you are using memory pools and placement new.
In Qt it is best to use delateLater() in order to avoid errors from unprocessed events. Also, widgets are by default created hidden, so you need to show() the widget.
So your code should be:
{//slot des()
if (temp) temp->deleteLater();
temp = new QPushButton(frame);
temp->show();
}

Answer 2

you can use delete to destroy objects. destroy method can only be called by the object itself. and qwidgets can be automatically recycled by the application. use pointer to point to the new memory space.