Please suggest me

Dear all my senior,

I am working seo last 2 years. I have only whitehat seo idea. last few weeks some one create unwanted link for my client website, i am so frustrated, I know its wrong way but I also want to drop my competitor webiste rank. So please provide me some trick that how to drop my competitor website rank.

Negative SEO is not allowed here mate.

try to avoid negative seo.

Yeah, it is not a good idea. Moreover, it doesn't work now. I guess, that your competitor made some spam links with some bad anchors. Add them to Disavow (and write a comment in your disavow file, that you have identified these bad links as your competitor's dark deeds) and forget about it. Google won't punish your website for this sh*t.