To remove an existing toolchain:
This will NOT uninstall the compiler from your computer; it will only remove MPLAB X IDE awareness of this compiler. To add the toolchain back, see Section 4.7.1 “Add or Change a Toolchain.”
If you want to uninstall a compiler from your computer, remove the reference to the compiler in MPLAB X IDE first, as specified above. Then uninstall the compiler. If you uninstall the compiler first and then start MPLAB X IDE, the toolchain paths will appear in red. To remove the reference to this uninstalled compiler, follow the steps above.