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That's a single ear hose clamp, there's a tool that looks like a big pair of nippers to install or remove them. If you search for them online you'll see how they work.
To be honest I usually just kind of rip them off with a pair of pliers and replace them with standard hose clamps. I think that's the condensate water drain tube so a standard clamp should work fine.
Use the points of a diagonal cutter to cut through the protruding ear and it will come off. If replacing with the same.type you'll need ear.clamp pliers. I use these on connections that need to be secure that will will not be taken apart often or maybe ever again.