Click the button located directly under their profile picture (or introduction card). Select Report/Block from the dropdown list. Click Block [Name] and confirm your choice. How to Close the Remaining Privacy Loopholes

Can a blocked person see my comments on a mutual connection's post?

Your conversation thread will remain in your inbox, but it will be frozen. Neither party can type a new message, and your name will display as "LinkedIn Member" on their end. The Subtle Loopholes: Can They Ever Still See You?