Those aren't page titles, they are widget titles. If you wanted to get rid of all the widget titles you could use.
HTML Code:
.widget-title {
display: none !important;
}
If you want to get rid of the widget titles only on certain widgets/pages you would use something like the following which works on the home page.
HTML Code:
#text-2 .widget-title {
display: none;
}
#text-2 {
margin-top: 20px;
}
The second part of that code moves the content of the widget down to line up with the text to the right.
It seems like it would have been easier to just create a site with no sidebars and put all the content on each page instead of using widgets.