1. Open the Health app on your iPhone.
2. Tap the profile icon on the top-right, and on the next screen, select Apps, under Privacy.
3. On the Apps page, select Health.
4. Now, if you want to delete all of the data at once, tap on the Delete All Data from Health button.
However, once you tap on Delete All Data from Health, all your data related to that particular app will be deleted at once. And, since the process is irreversible, you cannot retrieve the data back again. So, if you do not wish to delete the entire data related to health, and want to instead get rid of some listings, you can delete each data entry individually, as well.
How to delete Health data for different Activities
1. Open the Health app on your iPhone.
2. With the Browse tab selected, select a category under Health Categories. For instance, let’s assume you select Activity.
3. Now, on the Activity page, tap on any activity entry (say, Steps) that you want to delete, and on the next screen, scroll to the bottom and tap on Show All Data.
4. Here, hit the Edit button on the top-right corner and hit Delete All on the top-left side. Alternatively, you can hit the minus (-) sign next to each data to delete it individually.
