delete the buttons and label permenantly

[iswaryasenthilkumar]

i have two screen,
first screen contains 4 button and 1 label
second screen contains 4 button and 1 label
my app will start in first screen,,when i move to second screen first screen buttons and label should delete permenantly, so i used code

void Widget:: deactivefirstscreen()
{
delete button1;
delete button2;
"
"
delete label1;
}

void Widget:: deactivefirstscreen()
{
delete button1;
delete button2;
"
"
delete label1;
}

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i getting erro when command reached this method()
Error:

The program has unexpectedly finished.

The program has unexpectedly finished.

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please give me clarification for this
Thanks in advance