Found it!  The AzureML SDK appears to be storing auth credentials in ~/.azureml/auth/.
Deleting the ~/.azureml directory (which didn't seem to have anything else in it anyway) did the trick.
I have two or three sets of Azure credentials for Work, Work Admin, and Personal.  This morning, I clicked the wrong login credential during an interactive login while doing some local development.  My local dev app now has an identity of me@company.com, when I need my identity to actually be me@admin.com.  Because I clicked the wrong identity, my application immediately starts getting obvious authorization errors.
My implementation is pretty naive right now, and I'm relying on the Python Azure SDK to realize when it needs to be logged in, and to perform that login without any explicit code on my end.  This has worked great so far, being able to do interactive login, while using the Azure-provided creds when deployed.
How can I get my local dev application to forget the identity that it has and prompt me to perform a new interactive login?
Things I've tried:

Turning the app off and back on again.  The credentials are cached somewhere, I gather, and rebooting the app is ineffective.
Scouring Azure docs.  I may not know the magic word, and as a consequence many search results have to do with authentication for users logging into my app, which isn't relevant.
az logout did not appear to change whatever cache my app is using for it's credential token.
Switching python virtual environments.  I thought perhaps the credential would be stored in a place specific to this instance of the azure-sdk library, but no dice.
Scouring the azure.identity python package.  I gather this package may be involved, but don't see how I can find and destroy the credential cache, or any out way to log out.
Deleting ~/.azure.  The python code continued to use the same credential it had prior.  ~/.azure must be for the az cli, not the SDK.
How do I get my local python app to forget its Azure credentials so I can do a new interactive login?