I'm using uBlock origin. The rule is:

  stackoverflow.com###hot-network-questions

I've used the selector tool of uBlock to do it.

Edit: more on this: https://meta.stackexchange.com/questions/222721. Linked in one of the answer is an extension: https://chrome.google.com/webstore/detail/sidebaroverflow/lh...

There are also other solutions on that page.