How to remove a list of spammed-discussion-with-password?

hello

In my EasyDiscuss, I had a lot of spammed discussions.
Following your advice, I removed the right for guest to create & discussion.

Then I removed 90% of the spammed discussions but some of them have been created with a password (small 'lock' icon) and I can not remove it.

I selected the spammed discussions with password and try to 'unlocked' them (button 'unlock') but I can not.

<see capture in attachment>

My question: How can I select a list of password discussions then remove it?

Thanks
Henri