Once auto-detected toolchains can't be removed

What happens

Start Qt Creator once e.g. with a mingw gcc in the PATH. Qt Creator will auto-detect the MinGW toolchain.

Restart Qt Creator without the MinGW gcc in the PATH. THe toolchain is still listed in the 'Compilers' tab of Build&Run Settings. The 'Remove' button is enabled, but does nothing.

What I'd expect to happen

When starting Qt Creator in a different environment I wouldn't expect compilers detected from the PATH to show up again.

Alternatively, one should be able to remove such auto-detected toolchains via the 'Remove' button.

Workarounds

Seems one has to manually modify the toolchains.xml file, or nuke the complete settings, to get rid of the compiler.