Code:

function CompactDatabase(ADatabasePathName : String) : Boolean;
var
  JE      : TJetEngine;
  sdbTemp : String;
  DAO     : OleVariant;
begin
  JE := nil;
  try
    JE := TJetEngine.Create(Application);
    result := FALSE;
    sdbTemp := IncludeTrailingBackslash(ExtractFilePath(ADatabasePathName)) + IntToStr(GetTickCount) + ExtractFileName(ADatabasePathName);
    If FileExists(sdbTemp) Then
      DeleteFile(sdbTemp);

    try
      DAO := CreateOleObject('DAO.DBEngine.120');
      DAO.CompactDatabase(ADatabasePathName, sdbTemp);
      result := TRUE;
    except
    end;

    If DeleteFile(ADatabasePathName) Then
      RenameFile(sdbTemp, ADatabasePathName);

    If FileExists(sdbTemp) Then
      DeleteFile(sdbTemp);
  finally
    If Assigned(JE) Then
      JE.FreeOnRelease;
  end;
end;

...

procedure TForm.CompactDB;
begin
  DatabaseConnection.AfterDisconnect := DatabaseConnectionCompactIt;
  DatabaseConnection.Close;
end;

procedure TMainWindow.DatabaseConnectionCompactIt(Sender: TObject);
begin
  DatabaseConnection.AfterDisconnect := nil;
  CompactDatabase(IncludeTrailingBackslash(ExtractFilePath(ParamStr(0))) + 'base.accdb');
  tblRaw.Active := TRUE;
  tblProcessed.Active := TRUE;
end;