If you have any trouble on facebook where someone is being a nuisance, there are ways in which you can handle it.  If it is that you are no longer friends with someone, you can either delete the contact of you can use the facebook block.  The block means that the person which you were in contact with can no longer see your details and they will know you have blocked them so there will be no further hassle from them!  The delete means that you have completely taken them off your friends list altogether.  If there is any abuse used by someone on there, you can take further steps to action them being reported with facebook.  For more serious matters, you need to contact the Police if there is any form of bullying as this will be classed as a serious matter.  Facebook will n to tolerate any bullying or abuse so it really would need  reporting as soon as anything like this starts.