Hello,
Please avoid insulting each other, as well as inappropriate language such as telling each other to commit suicide.

As for the original question, you can report these players either in game or on this subforum by using the Misbehavior Report thread. Here is the link:

https://forum-narutoen.oasgames.com/page/show-post-52319-1.html

Please note that you will need a full screenshot to report a player which will include your server time/date stamp in the upper left hand corner of your screen (NOT your local computer time taken on the lower right hand corner of your desktop), as well as your opponent's server number, which can be obtained by hovering over their portrait in the upper right.

Thank you, and please be kind to each other.