Even the best poker players can't remember every opponent, and that's where Player Notes come in. Notes are a simple, private way to keep tabs at the competition at your current table and in the future -- just in case you forget to hold a grudge.
You can add a by visiting a player's profile or while playing a game at a table.
From the Profile page, just click the Add Note link just below the Send a Message button:
And the important part! During a game:
You can remove a note that you've added to a player's account by viewing their profile. On the right, you'll see a section called "Player Notes" with an "Edit Note" link.
You can then click to edit the note you have there. Delete the note and click "Update Note", and you're done! :)