Code:
uses
  WinInet;

procedure DeleteIECache;
var
  lpEntryInfo: PInternetCacheEntryInfo;
  hCacheDir: LongWord;
  dwEntrySize: LongWord;
begin
  dwEntrySize := 0;
  FindFirstUrlCacheEntry(nil, TInternetCacheEntryInfo(nil^), dwEntrySize);
  GetMem(lpEntryInfo, dwEntrySize);
  if dwEntrySize > 0 then lpEntryInfo^.dwStructSize := dwEntrySize;
  hCacheDir := FindFirstUrlCacheEntry(nil, lpEntryInfo^, dwEntrySize);
  if hCacheDir <> 0 then 
  begin
    repeat
      DeleteUrlCacheEntry(lpEntryInfo^.lpszSourceUrlName);
      FreeMem(lpEntryInfo, dwEntrySize);
      dwEntrySize := 0;
      FindNextUrlCacheEntry(hCacheDir, TInternetCacheEntryInfo(nil^), dwEntrySize);
      GetMem(lpEntryInfo, dwEntrySize);
      if dwEntrySize > 0 then lpEntryInfo^.dwStructSize := dwEntrySize;
    until not FindNextUrlCacheEntry(hCacheDir, lpEntryInfo^, dwEntrySize);
  end;
  FreeMem(lpEntryInfo, dwEntrySize);
  FindCloseUrlCache(hCacheDir);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  DeleteIECache;
end;