Scruton, 34, has been troubled by a long-standing shoulder issue and not played since the final game of last season against Widnes Vikings.
He came through the Academy ranks at hometown Leeds Rhinos and won the 2007 Grand Final before helping Rhinos beat Melbourne Storm in the World Club Challenge the following year and then retaining the Super League title.
Scruton went on to make more than 100 appearances for Bradford Bulls before a fine three-year stint with Wakefield Trinity, joining the Robins in 2017.
“Obviously it’s pretty devastating, the thought of not ever playing rugby ever again,” he said.
“It’s been a big part of my life for a long time, and it will be hard to get head around.
“But it’s for the best and on the surgeon’s advice it was my time to call it quits.
“The whole process has been tough but I can’t thank my family enough who have supported me from day one to today, and I’d like to place on record my thanks to Tim Sheens (KR coach), who has been absolutely class throughout the whole situation.
“I’d like to thank every supporter and every team-mate I’ve had the honour of playing with across my career, they won’t be forgotten.”
Jewitt, 32, has also left the Robins.
The former Wigan Warriors and Salford Red Devils forward, who played in the 2014 Challenge Cup final for Castleford Tigers, joined Rovers in 2017 after a brief spell in Australia.
He was contracted for 2020 but has played just three games this term following a succession of injury problems.
Although there are no plans to retire immediately, Jewitt is exploring options off the field.
“It felt like the right decision,” he said.
“At the end of the day, the club want a player on the field week in week out and I’ve not been able to give them that.
“Over the last few months I’ve been unable to be consistent and I've had to take a month out of the game with concussion on medical advice.
"From the club’s point of view I understand on wanting a player out there, and from my point of view that’s frustrating as I want to be out there but injuries have held me back.
“However, we leave on great terms. It was a mutual decision and there are no hard feelings at all.
“I’ve been working over the last five or six years doing different courses on counselling, sports psychology, mental health and welfare.
“It’s my passion, and I’d love to work in sport and particularly rugby league. My door is open.
“I’d like to say a massive thank you to the KR fans; thank you, I’ve loved playing there, every minute of it.
“They have a great fan-base and I’m sad that I’ve not been able to give them what I’ve been capable of.”