I had a forum that I installed a while back and then removed it a while after that. In that time, it seems the forum received all kinds of spam sign ups and posts that I didn't even know about. In looking at my stats, I'm seeing a ton of 404 errors and most of them are related to forum pages that don't exist. Is there an easy way in Google webmaster tools that I can tell google to remove everything under the /forum folder of my site from its index?
Webmaster tools > Site > Optimisation > Remove URLs
But I do not know how easy it is to request the removal of multiple URLs
Well 404 occurs in many ways like below:
You delete a page on your website and don't 301 redirect it
You change the name of a page on your site and don’t 301 redirect it
You have a typo in an internal link on you site, which links to a page that doesn’t exist
Someone else from another site links to you but has a typo in their link
If you are getting good links to a 404’d page, you be supposed to do 301 redirect it to the page the link was supposed to go to, or if that page has been removed then to a parallel or parent page. You do not have to 301 redirect all 404 pages. This can in fact slow down your site if you have way too many redirects.
Vince the OP knows why he has the errors and is trying to tidy up the Google links to the site:
I had a forum that I installed a while back and then removed it a while after that.
Well, it actually worked and it worked quickly! They give you the option to remove everything under a directory. So I just specified /forum (and everything under that) and today it says they were removed. Sure enough, I did a google search and none of those forum links are in google's index. However, I'm still getting the 404 things in the stats because I'm still getting clickovers from referring pages (also spam) Is there any course of action one should take for this?
If the pages are not important for you leave them with proper 404 header. After a while Google removes them from their database.
If some URLs are important, use 301 redirect.
Following up hundreds of 404 errors in Google webmaster tools is a daunting task. Use your time on someother useful thing.
If those pages are removed from Google index than no need to worry about.. I think, Google webmaster tools always take sometime to remove it from there so just wait for some time and they will removed from GWT as well... Also, I suggest you to generate a fresh sitemap and submit it.
Better create new pages and do 301 redirect so that you do not lose link juice
create a custom page for 404 error