Deflating air-filled items, from pool rafts to soccer balls, generally requires you put pressure on the valve to force the air out. This can get tiresome fast, but redditor h2orat solved that problem with a binder clip:
A few months ago, I was required to deflate and store several inflatable pool rafts for the winter. The only way to allow for the air to escape was by "pinching" both sides of the valve and then placing pressure on the raft. Halfway into the first raft, I decided to try and find a better way to complete the task. I was able to find a binder clip and it sped up the processes considerably.
Even if you're not dealing with a valve, binder clips can still help with deflation. My air mattress requires you to push a button to inflate and deflate it, and it's an awful button that's hard to hold down. A large binder clip did the trick there, too.