The Disavow tool, offered by Google in the Google Search Console, is used to remove links to a website that are negatively affecting the website’s SEO. These are often spam links, or links that only serve to see a website demoted in Google’s SERP. Google suggests using this tool only after a webmaster has contacted the linking website to ask for the link to be removed manually.
Google also warns that its Disavow tool can be used incorrectly, which can actually have a further detrimental effect on your page rank. As such, it’s highly recommended that webmasters read a guide on how to use Google Disavow before beginning to target and remove links.
Backlinks are of course important for technical SEO, and the right backlinks can have a positive impact on your page rank. But if your rank is suffering from a number of spam links, Google Disavow was created to help you remove those bad links and mitigate those ill effects.
One spam backlink to your website is unlikely to warrant the use of Google Disavow. But if several poor-quality backlinks are impacting your SEO, Google Disavow is the recommended solution to increase your page rank once more.