Disavow links

[JasperSEO]

I am working on an account that has had several seo companies
over the past year so around every corner I discover something new. One the
things I have found are that majority of links to the site is coming from an
outside blog but digging deeper I found that the blog is actually on the same
server as clients. Should I disavow links from that blog or should I leave it
alone?

[MikeRoberts]

If the link isn't hurting you then why would you want to hurt yourself by telling Google to disavow it?

As Irving mentioned, the Disavow Links tool is a last measure not a go-to tool for every occasion. If bad links are really hurting your site then start reaching out to those other webmasters to remove the bad links (or at least nofollow them). If you've been algorithmically penalized due to bad links then you'll also need to start working on building a better, more robust link profile through outreach and try to grab some really good ones to help counteract the bad. If all works out well then offending sites will remove the bad links (hopefully without needing to pay), those links from good sites will show that you're working towards improvement and then after a refresh you'll hopefully see rankings start to bounce back. If people won't remove your links, are asking for exorbitant amounts of cash, or are flat out ignoring you... then you can consider the Disavow Links Tool.

[irvingw]

I wouldn't draw attention with the disavow file unless your boxed in. Google clearly said it should be used as a method of last resort and they would even prefer that you write your story of link removal attempts in comments in  the disavow file. Try to contact the blog editor or webmaster and ask to remove or nofollow your links. You may even offer payment for the removal.