The "This site may be hacked" notification won't be removed until the webmaster of the site takes action.
Try these steps to fix your website:
1、Register and verify your site in Google’s Search Console. 2、Sign in to Search Console and check the "Security Issues" section to see details of sample URLs that might be hacked. Fix the security issue that allowed your website to be infected. Otherwise, your site is likely to be reinfected. 3、Read our resources for hacked sites for detailed information on how to fix your website.
4、Request a review in the Security Issues section in Search Console when your entire website is clean and secure. After we check that your site is fixed, we'll remove the "This site may be hacked" message.