Can't access my own organisation

Rachel_Jackson Hi, don't I think I understand exactly, but to start with do this using Incognito session as you don't want mixed up credentials.

If you have a Teams free org. you can manage it yourself https://portal.azure.com

If you are a guest user at other organizations I suggest you leave them using the "Access Panel" option.

https://docs.microsoft.com/en-us/azure/active-directory/external-identities/leave-the-organization

If you can't leave the org. you'll have to reach out the concerned admin to remove your guest account from their Azure AD (and the Azure AD recycle bin as well). There's a 24 hour delay before permanent deletion of the account.

You should also sign in to your personal account settings (the personal email address) to verify that you're not using any aliases or associated addresses to remove any link between them.