Warframe chats have the ignore function implemented for a quick and easy fix! To ignore users in chat simply type:
(repeat this process to un-ignore the user)
This should be the first thing you do if someone is bothering you in an online chat.
If you notice users constantly spamming, using offensive language, harassing, or life-threatening against you or your friends, report them by right-click the user's name and select "Report Player" then select the appropiate catergory. Make sure to provide a public shared screenshot link of the chat and other details.
This document will be updated should any new information about this topic arise.