Here are some of the ways to achieve that:
LTIR:
The Bruins could put defenseman Charlie McAvoy's $9.5 million, Brad Marchand's $6.67 million and maybe even Matt Grzelcyk's $4.5 million on LTIR, which would create about $19.3 million of cap space. All three are expected to be out of the lineup until at least late November to December, or even longer.
However, the team would, of course, have to make up that space they filled with a free agent signing once those players are healthy and ready to return (i.e.. Vegas Golden Knights and Jack Eichel).
There are always those teams like the Anaheim Ducks who have a lot of cap space that is willing to take on a player's contract with the addition of a draft pick.
TRADES:
The Boston Bruins have too many left-shot defensemen, so that's one area where they could shed some cap from the roster. Other options would be veteran forwards, which are still valuable to several NHL teams.
OPTIONS:
Matthew Grzelcyk (D) - $3.687 million cap hit through 2023-24.
Mike Reilly (D) - $3 million cap hit through 2023-24.
Derek Forbort (D) - $3 million cap hit through 2023-24.
Craig Smith (RW) - $3.1 million cap hit through 2022-23.
BUYOUT:
The only player with a contract terrible enough for the club to consider buying out is veteran Nick Foligno. According to CapFriendly's buyout calculator, the Bruins would save about $1,933,334 in cap space during the 2022-23 season; however, they would also have a cap charge of just under $1 million for 2023-24.