I have found that the best way to deal with parental issues is to address them before they become a problem, starting from the very first day of practice. Schedule a parents' meeting as soon as possible after your team is formed. Insist that all your parents attend. Prepare for the meeting and have a complete list of team rules and a schedule of games and practices. At the meeting, introduce the team concept.
Every player is a very important part of the team regardless of ability.
The team needs support and help from parents. Encourage the parents to attend the games. Insist on team spirit and pride. The team comes first. The team meeting is your opportunity to make it clear what your rules are.