The three are out of contract and will be allowed to move elsewhere as free agents after playing their parts in County's seventh-place Scottish Premiership finish.
Goalkeeper Fraser joined the club in 2011 and featured 10 times this season, Cooper featured 17 times while Glen made 16 appearances.
Adams thanked the three for their contributions to the side and says that their exits will not be the last ahead of the new campaign.
"All three of the players have done well for us," he told the Daily Record.
"Michael Fraser was part of our championship-winning team and enjoyed good runs in the team in our first two Premiership seasons.
"Gary and Alex also made good contributions to the first team and we wish all three of them well in the future.
"What all three have in common is a need for regular matches and that is something I wasn't in a position to offer any of them.
"There will be more to follow and we're in the process of speaking to all of the players who will and will not be offered contracts."