//Contactpersoon verwijderen
private void DeleteContactperson()
{
ContactPerson c = new ContactPerson();
c.ID = _contactperson.ID;
c.Name = _contactperson.Name;
c.Company = _contactperson.Company;
c.JobRole = _contactperson.JobRole;
c.City = _contactperson.City;
c.Email = _contactperson.Email;
c.Phone = _contactperson.Phone;
c.Cellphone = _contactperson.Cellphone;
ContactPerson.DeleteContactperson(c);
MessageBox.Show("De contactpersoon is verwijderd");
OnPropertyChanged("Contactpersons");
}