"Sorry, we are in batchmode..." Bug found?

I’m trying to remove the passphrase from my private Gpg4win encryption key. I’m using it with Mozilla Thunderbird and Enigmail. Whenever I try to remove the passphrase I get the error message in this screenshot:
To summon up:
“Sorry, we are in batchmode - can’t get input”

I can replicate the issue at will on several virtual machines using different versions of Windows, so it seem to be a general issue somewhere. Perhaps even a bug.

So, how can I remove the passphrase?

I apologize if I should be unable to reply for the next few days, but I will definitely be back as soon as I can. I hope someone out there can help as I am trying to promote the use of GnuPG for email encryption to the less technical users.