Crichton has spent five years on the Partick Thistle staff, but has decided to move on to focus his attentions on his own Glasgow-based clinic.
Club doctor Allan Robertson and physio Ross Anderson will remain at the club ahead of the Jags' second season in the SPFL Premiership. Thistle are close to announcing who will replace Crichton in the Firhill medical room and Archibald said: "Kenny is moving on and we certainly wish him all the best for the future.
"He has been a vital part of the club for the last five years. You need a good medical department, we have had the doc here for 40 years, and Kenny has done a great job for us.
"There was a spell when I came back, and George Hannah left, where we went through three physios in a couple of years and it was a bit of a nightmare.
"We have got a lot of plans for the infrastructure in terms of medical people, sports science, scouting, everything."
Crichton has been a key part of the Thistle backroom staff for the last five seasons and leaves the club just weeks after Archibald's side confirmed their status as a Premiership club once again for next season.
He has previously worked at Queen of the South, Gretna and Falkirk and the man with the magic sponge has hailed Archibald for the job he has done in cementing Thistle's place in the big time.
Crichton said: "The time I've spent here and the people I've worked with have been the best in my career. To see how the gaffer and Scott Paterson have developed over the last season and a half has also been fantastic."
Meanwhile, Thistle will head to Murcia for a pre-season training camp ahead of the big Premiership kick-off.
Archibald's side will spend a week on the continent before returning to face Dumbarton. They have also lined up behind- closed-door games with Cowdenbeath and Morton.
The Jags also hope to line up matches at Firhill later next month.