Hi Erin,
If you are a guest to a tenant, you can safely leave the organization and it should be removed from that tenant as described below:
When a B2B collaboration user leaves an organization, the user's account is "soft deleted" in the directory. By default, the user object moves to the Deleted users area in Microsoft Entra ID, but permanent deletion doesn't start for 30 days. This soft deletion enables the administrator to restore the user account, including groups and permissions, if the user makes a request to restore the account before it's permanently deleted.
Cited from https://learn.microsoft.com/en-us/entra/external-id/leave-the-organization#account-removal
How to leave an organization
Why can’t I leave an organization?
If this is helpful please accept answer.