OK so if you want to remove a title for 'Pages', you have to go to themes > template editor then find the page.liquid template. Find a line of code which is something like this:
<h1>{{ page.title }}</h1>this is what is outputting the title on pages. You have to 'comment out' this line so that this line is not shown in the front-end. Commenting out code is better than deleting altogether as you keep the original code just in case you need it in the future. Comment the page title out lke this:
{% comment %}<h1>{{ page.title }}</h1>
{% endcomment %}Then the page title will no longer appear.
NOTE: It's a good idea to duplicate the Minimal theme and edit the files in the duplicate one. That way you can refer to the original theme files if need be.