It’s very important when link building to stay clear of negative SEO. You should get links naturally, and going out and buying links is considered unnatural or blackhat SEO and Google will catch you and give you a penalty. When you have a penalty, you need to get the toxic links removed, and there is speculation to what is the best way to do this. You should NOT use the disavow tool; as this is not it’s purpose. The best way to get out of a Google penalty is to conduct a link audit to identify the toxic links and get them removed; so that Google can see that you have tried to remove the links yourself.