You can block another person by visiting their Quora profile page. Click the “...” and select “Block”.
If you block someone, they will not be able to follow or subscribe to you, send you messages, comment on your answers, notify you if you're @-mentioned by them, or send you A2A requests. Learn more about what happens when you block someone at What happens when I block someone on Quora?.
To see the users you’ve blocked on the Quora Platform, you can visit the “Blocked & Muted” section of your settings at www.quora.com/settings.