procedure TForm1.OpenAnExistingPowerPointFileAndSaveAs(Sender: TObject);
var
   PowerPointFileName, PowerPointFileNameNew: String;
   PowerPointApplication, PowerPointPresentation: Variant;
begin
     //be sure ComObj and Variants units are included in the "uses" clause

     PowerPointFileName := 'C:\PhysiologyWeb\delphi_code_examples\powerpoint_file.pptx';        //replace file name with the name of your file
     PowerPointFileNameNew := 'C:\PhysiologyWeb\delphi_code_examples\powerpoint_file_new.pptx'; //replace file name with the name of your file

     PowerPointApplication := Null;
     PowerPointPresentation := Null;

     try
        //create PowerPoint OLE
        PowerPointApplication := CreateOleObject('PowerPoint.Application');
     except
           PowerPointApplication := Null;
           //add error/exception handling code as desired
     end;

     If VarIsNull(PowerPointApplication) = False then
        begin
             try
                PowerPointApplication.Visible := True; //set to False if you do not want to see the activity in the background
                PowerPointApplication.DisplayAlerts := False; //ensures message dialogs do not interrupt the flow of your automation process. May be helpful to set to True during testing and debugging.

                //Open PowerPoint Presentation
                try
                   PowerPointPresentation := PowerPointApplication.Presentations.Open(PowerPointFileName);
                   //reference
                   //https://docs.microsoft.com/en-us/office/vba/api/powerpoint.presentations.open
                except
                      PowerPointPresentation := Null;
                      //add error/exception handling code as desired
                end;

                If VarIsNull(PowerPointPresentation) = False then
                   begin
                        PowerPointApplication.ActivePresentation.SaveAs(PowerPointFileNameNew);
                        //reference
                        //https://docs.microsoft.com/en-us/office/vba/api/powerpoint.application.activepresentation
                   end;
             finally
                    PowerPointApplication.ActivePresentation.Close;
                    PowerPointApplication.DisplayAlerts := True;
                    PowerPointApplication.Quit;

                    PowerPointPresentation := Unassigned;
                    PowerPointApplication := Unassigned;
             end;
        end;
end;