If, by room, you mean salary cap space, your only options are to either trade them or waive them and hope someone puts a claim on them.
If, by room, you mean roster space, then you can send them down if they have options. If they don't have options, they need to clear waivers first before sending them down. Keep in mind, however, if you demote a player once Spring Training begins, you risk that player suffering a demotion penalty which is typically a small loss of key ratings.