I got 10.000 + spam comments on my site and I would like to find a way to delete them without doing through the backend. I've already spent hours deleting them manually but there are to many.

Please help!

I had this issue and actually got a notice from google that they were going to suspend my analytic account because of all the spam. I didn't even know that one of my sites was filling up with thousands of spammed comments. What I did to delete all of them was to login to my control panel to access my Database Admin. Once logged in you'll want to go find:
jos_K2_comments

It will be here you will select it...you should see to the right of it a place to "empty" this. I clicked this and it deleted all my comments.

Only thing it didn't delete was the number of comments on my highlight of articles...they still state I have thousands in each article even though there are none.

Hope this helps!