Step 1: Log in to the WordPress Administrator
Step 2:Open an existing post/page or create a new post or page.
Step 3: Click on the Document properties in the right-hand column. You may need to click on the gear icon in the top right corner to display the right-column settings.
Step 4: Scroll down the right column until you find the Discussion section. Remove the check in the Allow comments checkbox to remove the option to allow comments.
Step 5: Click on Save Draft or Publish in order to save your changes. If the post/page is already published then the button used to save changes will be labeled Update.