Deactivating Challenges
In order to deactivate challenges you will need to specify the path to the private key (usually stored in JSON format)
The code will then use the inbuilt ACME library to deactivate the pending authorisations
I have tried to make the code not invalidate things that have already failed.
The HTTP challenge is used to invalidate the authz (it was the first one)
You can then run it again and see that as all pending authz are now invalidated the tool is smart enough not to try invalidating again
Note: the tool takes a 1 second sleep between each invalidation (so as not to throw lots of requests at a production server)
At 300 pending requests (which is what the current limit is) this will take about 5 minutes. So start it and go get a coffe 
Andrei