To fully reset the scale, you first have to delete registered users in the scale then you have to remove the scale from your WiFi network.
How to delete known users
From each user's account, go to MENU > Set up my devices > Select your Core (HS6) > Delete current user.
How to delete unknown users
If there are some unknown users (users you don't remember their iHealth account), please contact our support team providing a picture of the QR code printer on the back of the scale and a copy of your purchasing invoice and ask for the deleting of unknown users registered in your scale. S
How to remove the scale from your WiFi network
- Remove one battery and re-install it.
- Press the SET button located inside battery compartment. SET must be displayed on the scale.
Once the scale is on SET, remove the batteries if you do not intend to reinstall the balance immediately to conserve battery power.
*credit to Tanguy of iHealth Labs EU
https://helpcenter.ihealthlabs.eu/hc/en-gb/articles/207445469-iHealth-Core-HS6-How-to-reset-the-scale-