Google Disavow Tool is the way of telling Google which backlinks to ignore when assessing your site. Google’s team recommends that you only use the Disavow tool if you have a big number of spammy, low-quality links and if you are positive that the links are causing issues for your site. If you only have a bunch of low-quality links, it’s a good idea to try contacting webmasters of these sites first, asking them to remove the links.
SEO SpyGlass in-app disavow file generator lets you quickly create, manage, and export Google disavow files - so that you can then easily upload the files to Google Webmaster Tools.
In your SEO SpyGlass project, select the backlinks you'd like to disavow. Right-click the selection, and hit Disavow backlinks. Alternatively, you can disavow any specific link by clicking the x icon in the Disavowed column (on-hover).
In the menu that pops up, choose whether you’ll only be disavowing the backlink page you just added (Backlink), or the whole domain that links to your site (Linking Domain).
At this step, you can also add a comment to the records you’re disavowing. Comments are useful for your own future reference - whenever you review or edit your disavow file later, you’ll instantly see what kind of sites you were disavowing and why.
After you’ve added all links you’re about to disavow to the list, go to Preferences > Disavow/Blacklist Backlinks. At this stage, you can edit the comments by double-clicking any comment to make changes. Clicking Add lets you add links to your disavow list, and clicking Undo Disavow deletes selected records from the list.
In the Choose the action menu, you can select whether you'd like to simply disavow the backlinks, disavow and exclude them from all future updates you make in the project, or disavow and blacklist the links (have them removed from the project completely).
Once you’re happy with you disavow list, hit the Export button and select the folder to save the file in so that you can upload it to Google Webmaster Tools.
In the Google Disavow Tool, select your website and upload the disavow file you generated to tell Google which of your backlinks to ignore.