As much as those are annoying, you can't remove them. Website developer do that themselves and I don't think there's an add-on to remove those. Alas, I am just one of many volunteers here. I'm sure someone else will help you along the way that knows more than I.

there are many add/pop-up blockers, but banners and carousels are part of the page.

There may be a way for you to remove that. Load the web page. After, right click on the item. From the Firefox option list, select Inspect Element. Then IMMANENTLY move the mouse off the screen. A sub-window should now open. One of the entries should be highlighted. Mouse on top of that entry. Now you should see a colored block on the item. Right-click on the entry. From the menu, select Delete Node.

If you should make a mistake, do not worry. Just reload the page.

You can hide the container that keeps these images with code in userContent.css or the Stylish extension. You can use the built-in Inspector to get the 'id' or 'class' name of a specific item.

• https://developer.mozilla.org/Tools/Page_Inspector
• https://developer.mozilla.org/Tools/Page_Inspector/How_to

You can enclose rules in an @-moz-document block to apply the rules only to a specific domain.

• @-moz-document domain(support.mozilla.org) {}

• https://developer.mozilla.org/en/CSS/@document

Add code to the userContent.css file.

• http://kb.mozillazine.org/userContent.css

The customization files userChrome.css (user interface) and userContent.css (websites) are located in the chrome folder in the Firefox profile folder.

• http://kb.mozillazine.org/Editing_configuration

You can use the Stylish extension to make it easier to manage custom style rules.

• Stylish: https://addons.mozilla.org/firefox/addon/stylish/

• http://userstyles.org/help/stylish_firefox