bitcoin cli – How do I delete a wallet with an empty wallet name?

I think I created the following empty wallet at some point:

bitcoin-cli listwallets
(
  "",
  "mainwallet"
)

How do I delete it? "" wallet?

As per this answer, it doesn’t seem to have its own folder, so I’m not sure how to remove it.

It would be nice to get rid of all your wallets and start fresh, but bitcoind If you delete all of your wallet folders it won’t start, e.g. /mainwallet/ and /wallet.dat).