Azure Fundamentals sandbox is trying to launch a guest organisation rather than the default

Question

Without specific details, In myaccount.microsoft.com my Home organisation is set correctly to the firm I work with. In the guest area there is an organisation I did some temporary work for a number of years ago.

The microsoft documentation suggests you can press the Leave button but what happens is it is trying to authenticate against that organization and I get an access denied message which means I am unable to leave the organisation.

Where this is causing a problem is, going through the Azure Fundamentals training at one point it tries to launch a sandbox to experiment with. However, rather than authenticating against my Home organisation it is trying to authenticate against the guest organisation and of course getting an access denied.

So the question is, is there an alternative way to get rid of that guest organisation OR ensure that when the sandbox launches that it launches against my home organisation