WordPress used to enable comments on all pages by default, but thankfully that’s not the case anymore.
However, they are enabled on posts by default, and might still be enabled on your current pages depending on when you installed WordPress.
1. To stop future pages or posts you add from having comments, go to Settings > Discussion and de-select the couple options at the top dealing with comments and trackbacks. Note that this will only affect future pages, you will still have to do #2 below.
2. To remove comments from existing pages, go to the “Pages” area in your Dashboard (or whatever post type you have), and click “Quick Edit” within the pages you wish to remove the comments from. While in Quick Edit mode, you’ll see an option to allow comments which you can de-select.
It’s important to note that if your page or post already has comments, disabling them like the above will simply stop new comments from being added. Existing comments and pingbacks will still display. If you wish to remove them, you’ll need to delete the actual comments or pingbacks from your installation in the “Comments” area of your Dashboard.
If you wish to disable comments on certain post types but not others (not have them on pages, but do have them on posts), this plugin is great: Disable Comments