Cannot remove old/stale qt for mcu kits from Qt Creator

Repro steps (roughly):

• Install qt for mcu 1.6 and some corresponding sdks (nxp, renesas) via the maintenance tool
• Open qt creator
• Create some kits from sdks mentioned above
• Close qt creator
• Using the maintenance tool again, uninstall qt for mcu 1.6 and then install qt for mcu 1.8
• Open qt creator
• Create some kits for qt for mcu 1.8
• Attempt to remove kits for 1.6

Expected:

• Qt for MCU kits for 1.6 should no longer exist since it has been uninstalled
• Qt for MCU kits for 1.6 should at least be removable

Actual:

• Qt for MCU kits for 1.6 are still shown and the "Remove" button is grayed out