I don’t think he has released his delegates. I think that would signal that his campaign is over as opposed to suspended? From what I have read, that also requires him to repay any campaign debt.
I am ashamed to say, I never much paid attention to how other states conducted their primaries/caucus. I did this year. Very confusing...and I’ll bet if Rick releases his delegates, it will be equally confusing.
A good site to delve into the various rules/regulations of each state regarding their primaries is The Green Papers. They have one of the best collections of data that I’ve found and have used it as far back as the 2000 campaign.
http://www.thegreenpapers.com/P12/events.phtml?s=c