You (or the government) can ask a judge to order the civilian you don't like to leave. If the judge agrees, they have to leave. If the CYDL doesn't leave, you can ask a judge to order the police (or even you) to arrest and deport them. If the judge agrees, the police (or even you) can arrest and deport them.

If you don't have a judge's order to kidnap the person, then it's illegal by default.