Remove the key.
Unscrew the collar nut from the switch.
Then
Reach up through the fuse access panel if you have small hands to grasp the switch barrel.
or
Raise the instrumant panel (unscrew scerws).
Split the pedastal cowlings (unscrew screws).
Remove barrel. and pull off the wiring connector as you do so.
Fiddly job.
:wrench: