How do I get a Version of a toolchain and how to delete a toolchain

In the moment I fiddle with the STM32F1 blue Pill
and need to know what version of the STM Core I have installed and it would be nice to know how to uninstall a toolchain a install it new

Using IDE or CLI? What IDE? Using PIO Home via VSCode, you can see the version of STM32 installed, remove it, install another version, etc.

You do also get the version info via the CLI platforms commmand.

If you’re compiling code, it’s shown at the top of the build log - in this instance it’s the STM32 Arduino core, version 1.8.0, and the accompanying toolchain.