If you're about to sell your Apple Watch or pass it on to a friend or family member, it's important to clear your data off first. This is for your own piece of mind (given that it contains sensitive health and Apple Pay data and personal photographs, and could continue to burn through your data allowance if it's a Series 3 model) as well as courtesy towards the recipient.
Fortunately it's very simple to reset an Apple Watch. In this article we show you how.
Reset an Apple Watch from the companion iPhone
You can reset an Apple Watch on the device itself, but our preference would be to do so on its companion iPhone. (But keep the watch nearby, so that it's within Bluetooth range.)
Open the Watch app on the iPhone, and make sure you're in the My Watch tab (the lefthand icon from the menu along the bottom of the screen). Go to General, then scroll down and tap Reset at the bottom of the list.
Now tap 'Erase Apple Watch Content and Settings', the top option. You'll be given a chance to change your mind; if you don't want to, tap 'Erase All Content and Settings' to confirm.
For those who own a cellular Apple Watch Series 3, note that while this breaks the link with the data plan, and requires the watch to be re-enrolled to get data again, this does not cancel any watch-specific data contracts or subscriptions you've got with a phone provider. You'll need to contact your supplier separately to arrange for this to be dealt with.