Mac Photos Edit

If the photo is already in your Photos Library, you can also use the Retouch Brush to remove the address.

Open the photo in Edit, then click the "Retouch" brush in the sidebar and drag the brush across the object you want to remove. For example, when I want to clean up a screenshot made on my iPhone.

Retouching may leave a blurry patch at the first attempt. Then do it again, until you are satisfied. Or option-click to select a source for cloning.

If you prefer to do it in photos (Eg if you've taken a photo of the thing with the address on):

• Go into edit.
• Click the three dots in the circle
• Choose markup, and use whichever drawing tool you find easiest. One option is to draw a filled box over the address.

As Terence says - if the file is created outside of photos (say from a screeenshot) it can be easier to do it in the preview app, where the same markup tools exist.

Like léonie suggested:

All done right in the Photos library edit mode.

You can do that with Preview.