Nadjoh, evo ako nekome treba:
VAR MyPage:TRavePage;
text1,datatext1: TRaveText;
begin
Rvproject1.ProjectFile := extractfilepath(application.ExeName)+'Project1.rav';

RvProject1.Open;
RvProject1.SelectReport('Report1',False);
RvProject1.SetParam('var2',Jedit2.Text);
with RvProject1.ProjMan do
begin
MyPage:=FindRaveComponent('report1.page1',nil) as TRavePage;
text1:=FindRaveComponent('text1',MyPage) as TRaveText;
datatext1:= FindRaveComponent('datatext1',MyPage) as TRaveText;
//if that and that = something then
text1.Text :='';//make the text invisible
RvProject1.SetParam('var1',''); //make the datatext invisible

end;
try
RvProject1.Execute ;
finally
RvProject1.Close;
end;

P.S.
Ovaj Rave je prilicno konfuzan iako je dobar