Bases - can't change the name of a property

What I’m trying to do

I have a property called “notetype” which was accidentally inputted as “notetype:”.

I now can’t add a new property called "notetype’.

It seems to be locked somehow as “notetype:”:

Things I have tried

I’ve tried editing the property, and tried creating a new one.

Somewhat like this? If so from what I can tell you should be able to select the Bases property and edit that property directly to rename from notetype: to the proper notetype