How to block div on website permanently using Chrome?

For this kind of thing, I normally recommend the Stylish Addon for chrome.

Browse to the site when you have installed teh addon and go to:

Stylish (Icon) > Manage Installed Styles > Write New Style. Give it a name and select "applies to". Give the domain of the site you want to remove the comments from and select "URLs on the domain".

use code similar to the following to hide the div:

.comments {display: none !important;}

Save, and you should notice the div is now hidden

EDIT: Stylish is now Stylus - you can download it here: https://chrome.google.com/webstore/detail/stylus/clngdbkpkpeebahjckkjfobafhncgmne

You can use Adblock Plus chrome or firefox extension. When enabled, click its extension icon and then click "Block element". Then you can click an element in the page that you want blocked.

Adblock Plus will then block that element each time it is found.