First of all, there's a procedure of verification and proving that the blacklisted domain is your property. Go to: https://www.google.com/webmasters/tools/security-issues and press "Add property now" Enter the URL of the property that you'd like to verify. Recommended / Alternate methods would appear. Follow the instructions provided on each
From the dropdown menu choose your domain provider.
Use your Google Analytics account. Asynchronous tracking code: https://support.google.com/analytics/answer/1008080
Use your Google Tag Manager account. Container snippet: https://support.google.com/tagmanager/answer/6103696
This method should be used only in case the others did not resolve the issue with the blacklisted domain. In order to have a link for verification
your admin Lucy domain must be changed to the target one.
Warning! During the procedure there would be no access to the default Lucy's admin path (for example, access.cloudsuperservice123.com)
by pasting it or creating manually a full copy of the file.
Now the target domain should be added to your property list here:
Here you can manage the issues with it, resolving security problems. Find the issue, request a review, and write a reason, that the site does not contain any harmful content. Please note, that the process might take a few days to finish. After it's finished the notification email should be received containing the result of a request.