First find the backlinks from google webmaster tools and check the most relevant backlinks and remove un relevant backlinks by using google disavow tool
The Google Disavow Tool is not designed for people just to come along to remove unwanted links with. Google want you to try and get the links removed first, or at least some of them. This shows that you have tried to remove the links before using Google's tool as an easy way out. It would be too easy for a penalized person to just use the disavow tool to remove the links and carry on with what they were doing before.
At The Link Auditors, we have many tools, designed for finding and removing backlinks. One tool in particular is the email tool. This tool, once the toxic links have been found, will automatically send removal requests to each webmaster linking to your site or blog etc. Getting links removed manually can take a long time, with no effect, especially if you have many links that need to be removed. With our tool, it does it all for you very quickly and with much more efficient results.
For example, if for any reason, some links have remained on your site after running this tool, now is the time to use Google's Disavow tool. They will see that you have removed most of the harmful backlinks, and will allow the tool to work and, if penalized, you can send a reconsideration request and you stand a much better chance of a better result in their SERPs.