I want to decrease the size of a file without rewrite it.

I realize that after reset a binary file by Reset(file,1), I can modify any byte in the file and can easy increase it's size.
But i don't know how to decrease the filesize by remove some bytes at the end of the file  but without reWrite it content!
Can anybody help me?
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something like this?

procedure DecreaseFile(const S: string; NewSize: Integer);
  F: file of byte;
  AssignFile(F, S);
  Seek(F, NewSize);

and you call it by

DecreaseFile('myfile.dat', 1024);

so if the file is a 4kB file it will now be a 1kB file.

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coldboyAuthor Commented:
thanks! Your answer accepted
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