Just in case you need to disable comments on your WordPress website, you can follow these simple steps. Go to the Dashboard. Now, depending upon what you want to change, choose from either Pages or Posts and locate the one you want to affect the change on.
On the Screen Options (marked 1 in the screenshot), lookout for the Discussion module (marked 2 in the screenshot) and see the different check boxes and the accompanying options. Uncheck both the boxes (marked 3 in the image) if you wish to prevent any kind of discussions on the page or post.
In case you want to remove the contact form channel of commenting but wish to keep allowing comments through Pingbacks or Trackbacks from other blogs just uncheck the box corresponding to Allow Comments, leaving the other one checked.
Also, you can do it the other way round, that is un-checking the box titled Allow Trackbacks and Pingbacks and checking the other box. This is done when you wish to allow visitors to put comments on the page but do not wish to entertain pingbacks and trackbacks from other blogs.
Once the desired changes are made, Update the post (marked 4 in the image).
You might be disappointed to note that there is no single button option to turn off comments from all the published posts in one go. However, the bulk edit feature of WordPress proves useful in such cases.
This is done when you enter the Dashboard by selecting all the posts you want to disable comments on and then choosing the required option from the Bulk Action drop down menu. However, you can easily turn comments off posts automatically after it remains active for a certain period.
Go the Settings > Discussions option and use the Other Comment Settings option to find the relevant option. Check the box next to the option, fill in the desired number of days, and save.