Having just done this recently myself, I will guide you in, so to speak.
Step 1: Find any post by the person you want to ignore - since they number about 80% of posts lately it shouldn’t be hard!
Step 2: Click on their avatar then click on their name
Step 3: Under the name it probably says normal - click that and two other choices come up, muted or ignored.
Step 4: Click ignored
They don’t disappear from the list of topics but their content does not appear when you read threads.