In GIMP 2.10.6 there's a
Units dialog (
Edit > Units) where you can add your own units of measurement, but there is no obvious way to remove them. How can you remove custom made units of measurement?
The units are stored in the
unitrc file. For Windows users this is located in the
AppData\Roaming\GIMP\2.10 directory. Here you can manually edit the unit entries.