If you don’t want to see Reddit ever again in search like I did, you can follow these steps:
Step 1: Install the extension from the Firefox store.
Step 2: Search Reddit.
Step 3: On your first search result drag your cursor over to the right on the drop-down arrow and select the crossed out eye.
Step 4: Hide all the Reddit suggestions on your first page.
Step 5: Now you won’t hear a beep again from that Snoo.
If you don’t want an extension, you can use this user script with Violentmonkey
https://greasyfork.org/en/scripts/1682-google-hit-hider-by-domain-search-filter-block-sites