How do I empty my storage

There is no "Clean All" button. But you can see what is taking up space on your iPhone here:

Settings > General > iPhone Storage. Go through the list and remove what you don't need. The apps at the top of the list are the ones that take up the most space.

If you're running out of space in iCloud, you can clean up there too, go to:

Settings > Apple ID > iCloud -> Manage Storage

Finally, you can also buy more space in iCloud, so you don't have to remove content. Remember that iCloud Storage and iPhone Storage are two different things.

The difference in the internal storage space in the iPhone and in iCloud.

What's the difference between device storage and iCloud storage? - Apple Support

You can see how to buy more space in iCloud here:

iCloud+ plans and pricing - Apple Support