Krestanovich, who took charge of the Elite League side at the start of the campaign after two seasons as a player, was informed that he was to be stripped of his post as coach, with the 56-year-old Gardner taking his place. His side has suffered a poor run of form of late: they have lost 10 of their last 12 games, culminating in a 7-2 defeat at Sheffield Steelers on Sunday.
It is understood that Krestanovich was contacted by Neil Black, the club owner, to inform him of Gardner's appointment, but was then asked to remain in a playing capacity. However, the Canadian said yesterday he felt he had to leave the team and supporters he has grown close to over the past 2½ years.
"I was told a few days ago by Neil that he was planning on bringing in a new head coach," said the 31-year-old. "It meant I would have to step down but he said he wanted me to continue playing. That wasn't really an option; there was no way I could have stayed.
"Things have been tough this year and there have been a host of circumstances and things that have gone against us that have been totally outwith my control. But, after being head coach up to this point, I couldn't just step aside and carry on as a player."
After making the decision to call time on his spell at Clan, Krestanovich met with the players yesterday morning to say his farewells.
A statement on the club's website stated that he will leave within the next two weeks, although it is unclear whether he will take to the ice again for Clan during that period. His next destination is unknown but the former Colorado Avalanche man is understood to be keen to remain in the UK.
"The hardest thing for me will be leaving Glasgow," he said. "I've loved my time here; my family are all settled. It's going to be tough to say goodbye to the fans because they have been amazing during my spell in Scotland. Things haven't worked out over the last few months but I'm still proud at what we've achieved. I'm going to carry on playing; I've got three or four good years left in me."
Gardner is expected to bring in some new players and will take charge of the side for the first time in the home game against Hull Stingrays on Saturday.