The plastic zip-ties that come on our boxes can be undone using the little plastic clip so they can be reused, but if they have gotten stuck or have pulled too tight to undo, you may have to cut them off.
If that happens, don't worry! Pop the damaged ones in the recycling, have a rummage around inside your box and you should find some spares.
Tie your lids back up and you're good to go!
Remember- all box lids need to be fastened for return else they won't be collected.