Altering or removing copyright ownership information, in IPTC or anywhere else, is a criminal offence in UK under the Read more

In UK law and most other countries, a copyright statement is not formally required, but if you use one (and you should) a valid copyright statement comprises 3 essential elements

• © - the in

Metadata is textual information embedded in an image file. Not all image file formats are capable of holding metadata, but JPEG, TIFF, PSD and most digital camera RAW formats support it.

No statement of copyright ownership is required by law, and its absence does not weaken the protection of copyright.

The short answer is that you cannot.

Watermarking can be of two types, visible or invisible.