Removing the comments form

At the bottom of each page on my site is this form:

‘Leave a Reply

Your email address will not be published. Required fields are marked’

And its associated comments box.

I want to get rid of this form as it isn’t necessary.
I know that i have to edit a PHP file, But I am unsure which one, and what to insert and where to insert the text.

I am a rookie when it comes to editing php, so and in-depth explanation would be much appreciated.

Thanks