In OBIEE 10g you can hide the Page Options for all dashboard and users, by using John's blog post.
In scenarios where you want to hide the page option for a specific dasboard page or users, groups. In those cases you can use this approah.
var body = document.getElementsByTagName('body');
var tabcls = body.getElementsByTagName("td");
for (i = 0; i < tabcls.length; i++)
tablcn = tabcls[i];
tablcn.style.display = "none";
Go to Page Option -> Edit Dashboard
create a separate section in Edit dashbaord layout, make sure that section is at the top of all other section.
To hide it for specific users/groups, go to Section Properties -> Permissions
For user Vinodh the page options would be hided.
For other user it would be visible,