For security purposes, once a user account is deactivated, Grove HR will block all log in to ensure the user can no longer access the company data.
If there is only one admin, Grove HR's mechanism will prevent the admin from deactivating their own account.
If you accidentally offboard your account, ask other Admins to help reactivate your account by performing a rehire. Once your account is rehired and you receive an invitation, you'll be able to reactivate your account.