Go to his profile and hit the Report button. Are you talking about the Level 61 Swiss player (
https://www.warzone.com/Profile?p=7280578239)? If so, here's the direct report link:
https://www.warzone.com/Report?p=7280578239On that report page, you probably want to select "They used highly offensive language," "They posted adult content or other inappropriate material" (if applicable), or "Other" (most of the categories on that page are just there to reduce frivolous reports, so "Other" encompasses many actual rule violations- like ladder manipulation or calling a lottery game "lotto" instead of "lottery" or telling someone they made a mistake in playing Idle; if your report best falls into the "Other" category, that's not a problem as long as it corresponds to a rule violation and/or problematic behavior).
This is the important part: fill the report description out thoroughly. Link to all games where Ackbar has harassed you in chat. Paste the logs of these chats with timestamps, if possible. If there's private or team chat involved, take screenshots and put them on image hosting websites (like Imgur) then link those in your report. Mods aren't omniscient so you have to give them what you have. Also- and this is where some risk comes into play- you may yourself have moderator action taken against you if you said something mean to Ackbar in return, and it's quite hard to predict how the mods/admins interpret their rules. So tread carefully if you think something in those games could be used against you. But in general you should be fine, this is just a warning in case you weren't able to keep your cool.
Good luck! If someone is griefing and harassing you on this site like that, then I hope the administrators and moderators apply the same liberal interpretations of the rules that they use when dealing with innocuous behavior from players they don't like.
Edited 3/6/2021 09:02:57