Watch storage
How do I clear storage from my watch?
Apple Watch Series 4, watchOS 9
Question marked as
To Free-Up Storage
For songs, see:
Remove music from Apple Watch - Apple Support
and for pictures, see the "Limit photo storage on Apple Watch section in:
Choose a photo album and manage storage on Apple Watch - Apple Support
To delete apps on your watch, see:
Delete apps from your Apple Watch - Apple Support
Also, try unpairing and pairing your watch again and restoring from the backup just created in the unpairing process. This deletes all temp and corrupted files and re-indexes the file system. This should result in no loss of data and in some cases can free a lot of storage.
Unpair and erase your Apple Watch - Apple Support
Set up your Apple Watch - Apple Support
Also see:
If you don’t have enough space to update your Apple Watch - Apple Support