Removing thousands of spam comments

[kwaifeh]

Hi Guys,
I am very new to CMS MS.
My clients have a website running CMSMS on apache.
We have thousands of spam comments in the forum section. They are pretty different so there isn't one keyword I could look for or anything like that.
What would be the easiest way to go about finding and deleting these comments?
Is there a module\plugin or even a different manual way?

Thanks!!!