Unlink one extra unwanted item from a thing

I’m totally new to Openhab and have installd Openhab2 on an RPi 3. I have used Paper UI to define
things and items connected to My Sensors Binding and all have worked well. I then wanted to define
the Basic UI and followed the instruktions in “Tutorial (Beginner)” and created a default.items file.
When I then looked in Paper UI there was to items connected to the same thing. I tried to remove
the link to the new item but got the error “ERROR:405 method not allowed” than I deleted the .items file but got another item with a different name. This can’t I remove neither. Is there any way to solve this?

Either create your items through text files (*.items), in this case you should set

PaperUI->Configuration->System-> switch “Simple Mode” at Items Linking to OFF

or leave Simple Mode on and let openHAB create your items automatically.

A mix of both is confusing and you cannot delete textual items through PaperUI or vica versa.