Justin Richards and Louis Dodds both hit hat-tricks while Marc Richards also got on the scoresheet as Phil Jevons and James Spencer netted consolations for the Shrimps.
Morecambe goalkeeper Barry Roche made several fine saves to keep the score down but the club still crashed to their heaviest-ever defeat in the Football League.
McIlroy said: "I want to apologise to the fans personally and on behalf of the players because what they saw was totally unacceptable.
"I wanted us all to go over to the fans at the end of the game and acknowledge their support but the stewards and police told us we had to get off the pitch as soon as possible as Port Vale were expecting a pitch invasion.
"Our supporters deserve so much better than they saw on Saturday and I felt for them."
Source: PA
Source: PA