I have uninstalled atmelsam platform. However, toolchain-gccarmnoneeabi failed to uninstall automatically. Is it possible to try to delete it manually one more time? Or is it safe to just delete the directory of the package?
After installing atmelsam platform one more time (throwing errors in process), then uninstalling it again, the package toolchain-gccarmnoneeabi was uninstalled too.
However, I’m still interested if it is possible to (un)install packages (not platforms) manually.
Please sorry, that is not possible with the current PIO Core. You can file feature request here Issues · platformio/platformio-core · GitHub