You can block users. Blocked users cannot comment on your addons and cannot rate them. Blocked users can also not write to you via direct message. But regardless, they can still download your addons.
- Open your settings.
- Click on "Blocked Users" in the navigator bar.
- Enter the username of the user you want to block.
- Click on Save.
When the respective user tries to message you or comment your files, it will state that they have been blocked.