Unfortunately, it’s impossible to change user's email address on Conrad Connect Platform. However, there is an option to publish current projects, create a new account, connect devices there and import published projects. The old account could be deleted afterward.
Since June 2018 Conrad Connect has introduced new services and features available on Service Marketplace. Previously created accounts have remained their preferences in gratitude to the first users, although accounts created after June 2018 have different account preferences. However, Conrad Connect platform is still open to everyone and free to use.