Question

هدف پلیس رفع مزاحمت ازشهروندان است

Answer 1

Police's goal /assigned duty is abatement of nuisence for the citizens (poeple).

Or,

Police's objective is to remove the inconvenience from the citizens /civilians /people.

Answer 2

The main aim of the police is to stop harassment of citizens. 

Or

The main aim of the police is to tackle anti social behaviours.