First af all, override the "CreateParams" method of your Form, by declaring this in either your Form's protected or public section: procedure CreateParams(var Params: TCreateParams); override; Then, in the actual CreateParams method, specify something like this:
procedure TForm1.CreateParams(var Params: TCreateParams); begin inherited CreateParams(Params); with Params do Style:=(Style or WS_POPUP) and (not WS_DLGFRAME); end;