If you're trying to hide all comments, just click on the "Edit" link above the comments. The "Edit" and "Respond" links there are used to switch between showing the comments section and the Edit section. Your browser should remember your last choice and show that section by default.

If you're only trying to hide some comments, please provide more info. This site really shouldn't have any unpleasant comments one would need to selectively hide. But if it's something like that, there is a userscript I wrote for another booru that allows you to blacklist members in the comments section.

If neither of those address the issue you're dealing with, please explain.