domain name on 404 error page

edit

I have askbot running on ask.mydomain.com. When I get 404 error page, I see following steps to take:

Other things to try:

• Go to mydomain.com
• Go to sitemap www.mydomain.com/sitemap
• Search ask.mydomain.com:

[search form here]
etc.

But I don't want to associate mydomain.com and ask.mydomain.com sites.
How can I edit Other things to try list?