From the HOME Menu, select "System Settings."
Scroll down the options on the left and select "Mii."
Select "Create/Edit a Mii."
Select "Mii List." Choose the Mii character you want to edit/delete.
Do you want to Edit or Delete a Mii?
Use the control stick or the directional buttons on the left Joy-Con to navigate through the different physical features for your Mii character, such as Face, Eyebrows, Nose, Facial Hair, etc. Use the right Joy-Con to select it.
When you are finished editing your Mii, press "Done."
Select "Delete," then "Delete" again.