If you can't access a home or accept an invitation in the Home app, there's a support document for you.
The Remove Home option should be used on homes that don't have accessories if the device is running the latest version of Apple's operating system. Apple support should be contacted if the user has a home with accessories.
If a home with no accessories is removed from the Home app, the invited user and home owner's devices need to be restarted as well.
In order to share control of the home, the home owner needs to remove any pending invitations to invited users. If an invited user doesn't accept the invitation within three hours, the invitation will end.
Just a day after the new Home architecture was pulled, Apple gave instructions. Apple is not allowing users to upgrade to the architecture at the moment due to a number of bugs that users have reported with the update.
HomeKit devices going missing, HomeKit Secure Video not working, and invitations to share the Home with other users failing are some of the issues with the architecture update.
The new Home architecture has been temporarily removed and will be reintroduced at a later date according to the support document.