How to Report Profiles for Violations:

• Open the profile fhat you’d like to report.
• Select the 'overflow' icon
• Select 'Report' and, then, select the type of issue you’d like to report.
• If you select 'They’re being abusive or harmful', Twitter will ask you to provide additional information about the issue you’re reporting. They may also ask you to select additional Tweets from the account you’re reporting, so they have better context to evaluate your report. They will include the text of the Tweets, you reported, in their follow-up emails and notifications to you. To opt-out of receiving this information, please uncheck the box next to 'Updates about this report can show these Tweets'.
• Once you’ve submitted your report, Twitter will provide recommendations for additional actions, you can take to improve your Twitter experience.

For more information: https://help.twitter.com/en/rules-and-policies/twitter-report-violation