Вам нужно будет использовать WinINet в Вашей TfrmMain: Uses WinINet; и добавить к TButton следующий обработчик btnEmptyCache:
procedure TfrmMain.btnEmptyCacheClick(Sender: TObject); var lpEntryInfo : PInternetCacheEntryInfo; hCacheDir : LongWord; dwEntrySize : LongWord; dwLastError : LongWord; begin dwEntrySize := 0; FindFirstUrlCacheEntry(nil, TInternetCacheEntryInfo(nil^ ), dwEntrySize); GetMem(lpEntryInfo, dwEntrySize); hCacheDir := FindFirstUrlCacheEntry(nil, lpEntryInfo^, dwEntrySize); if (hCacheDir <> 0) then DeleteUrlCacheEntry(lpEntryInfo^.lpszSourceUrlName); FreeMem(lpEntryInfo); repeat dwEntrySize := 0; FindNextUrlCacheEntry(hCacheDir, TInternetCacheEntryInfo(nil^ ), dwEntrySize); dwLastError := GetLastError; if (GetLastError = ERROR_INSUFFICIENT_BUFFER) then begin GetMem(lpEntryInfo, dwEntrySize); if (FindNextUrlCacheEntry(hCacheDir, lpEntryInfo^, dwEntrySize)) then DeleteUrlCacheEntry(lpEntryInfo^.lpszSourceUrlName); FreeMem(lpEntryInfo); end; until (dwLastError = ERROR_NO_MORE_ITEMS); end;