To open up the front seats whilst out of the vehicle, you'll need to push in the collars on the studs under the seats (the ones with a bl**dy great spring behind them).
I'd suggest you didn't remove the front seats, as they contain an airbag, which you need to keep disabled with a special plug in device (only available from a dealer, and then, only if they think you know what you're doing with it!).
Many people will suggest you don;t need to do this, but if you are wiping/hoovering the seats, the chances are you'll get a static build up which could trigger the bag. Best to do any cleaning in situ.
Cheers,
Mike