Chess.com's Terms of Service can be found by following the "User Agreement" link at the bottom of the page, including this one; further guidelines can be found in this forum post.

If you see something particularly offensive and there's no Moderator in the Help & Support chat room, report it via Contact Us - Chess.com Member Support and FAQs ; a Support team member will contact you via the e-mail address you supply. You should get an immediate, automated acknowledgement before the Support team contact you up to 48 business hours later.

If something is not urgent, you can report it via the other person's popup profile and clicking on "More" and then "Report" - these reports may not be actioned immediately, but are definitely accumulated and reviewed as more reports are received for a given member.

Both of these links can be found in the Help menu under "Report Abuse".

I've done paid work for Chess.com in the past, and even after that ended, still had the staff tools to help out the moderator team. That came to end, I had a break, and had a stint as a regular moderator; I have now returned to civilian life under my personal account rather than this official one.

Former_mod_david