You'll need to access your database (via phpMyAdmin, or some other database management tool) and access the wp_amelia_providers_to_outlook_calendar table (please note that wp_ is the default database prefix, but on your end, it could be anything, so look for your_prefix_amelia_providers_to_outlook_calendar table). Delete all rows from that table, and after that, you should be able to connect your employees to the Outlook Calendar.
