You can add any Commander to the Blacklist, i.e. block them.

Blocked Commanders cannot send you personal messages and you will not see their messages in the Common Chat.

To add a Commander to the Blacklist, tap on their name in the Chat and tap the "To the Blacklist" button in the Commander menu window that appears.

You can also add a Commander to your Blacklist from the Mail window. To do this, select the message of the Commander from the messages list, then tap their userpic, and tap the "Block" button in the information window that appears.

To remove a Commander from your Blacklist, go to the Menu and tap the Blacklist section. Then select the Commander you wish to unblock by tapping on the free space to the left of their name and userpic and tap the "Unblock" button at the bottom of the screen. You can unblock several Commanders at once by selecting them one by one in the list.