If you want to BLOCK a War Metal player, keeping him away from your WM wall and also unable to join your Epic Bosses events (those started by you) use the following link shown here, replacing the word "IdPlayer" by his/her ID number on Facebook.
Then, copy and paste the link into your browser and hit enter. And you're done. Although open your Epic Bosses page, the one who wanted to block will be already blocked.
Then, copy and paste the link into your browser and hit enter. And you're done. Although open your Epic Bosses page, the one who wanted to block will be already blocked.
To unblock him, just search his name in the block list (in the Epic Bosses section)