First, click on the player in-game, so their name pops up at the top left corner. After that, click the name, so a drop-down menu appears, and choose Ignore. Your child will no longer see them in the game, and they will not be able to see or contact your child anymore.
If you have concerns regarding a certain player behaving inappropriately in-game and not following our chat rules, please contact our Customer Support Team and provide them with the character name of that player so that we can investigate further. Please add the time and date of when the incident happened.