There's a really helpful article in the FAQ ion dealing with rude or abusive opponents: https://support.chess.com/customer/en/portal/articles/1444877-what-should-i-do-if-another-member-is-rude-or-abusive-
Please don't name & shame people in the public forums, but follow the above guidelines and report them if you feel that this is warranted.
For not accepting [No naming and shaming - Mod.] rematch request, this was posted on my wall right afterwards:
Run little coward run LOL!!! [edited for language - Mod.]