Ikea kitchen planner with own appliances and blue wall?

Hello, we are currently planning a kitchen. Whenever we add our own electrical appliance to the plan, two blue walls appear. How can these be removed? Or how can we create our own tall cabinet? Thank you very much for your help. Best regards Findus

The walls disappear as soon as the device is no longer actively selected. How do you expect to build a tall cabinet for devices?