How to delete health data. It’s taking a lot of space

Please see the pic below which is self-explanatory.

How to back up and delete your Apple Health data | AppleInsider

Manage Health data on your iPhone, iPod touch, or Apple Watch -Apple Support

View your data in Health on iPhone - Apple Support

Delete data: Tap Show All Data below Options, swipe left on a data record,

then tap Delete. To delete all data, tap Edit, then tap Delete All.

There's some other support info links online or maybe in your iPhone too.

..Hderna..

Perhaps due to iOS/iPadOS Data ~ not going anywhere.

.Documented phenomena in most iOS14 or later devices.

4. If you delete the Health app, all of your data remains on your device.

See: "What happens when you delete built-in apps from your device"

(Beneath content, in this Apple Support article ~ in numbered section)