Open your photo in Photoshop
Save this photo as an original and a copy before you do anything else. Here's how:
• Go to File>Save As
• Name your photo with a name that is either assigned or that you will know belongs to what you are working on. For example: cd cover_steve campbell.
• Save this as ORIGINAL. For example: cd cover_steve campbell_ORIGINAL
• Now go to File>Save As and save this photo as a copy. For example: cd cover_steve campbell_copy
Now, do all your work on the copy. Keep your original so you can reuse it if you need to.
Go to the Magic Eraser
http://stevecampbellhillwood.blogspot.com/2015/12/photoshop-tools-explained.html
With the Magic Eraser selected, click on the green areas to delete them.
If you delete too much, you can undo.
http://stevecampbellhillwood.blogspot.com/2015/12/to-undo.html
To delete all the green areas, you will probably need to zoom in.
Use the Zoom Tool
http://stevecampbellhillwood.blogspot.com/2015/12/photoshop-tools-explained.html
The Zoom Tool works like this. Click on it to zoom in (or magnify). To zoom out (or minimize) press and hold the option key and click.
You could also go to Window>Navigator and use the Navigator window.
To erase the small green areas, switch to the Eraser Tool. Stop using the Magic Eraser.
http://stevecampbellhillwood.blogspot.com/2016/01/eraser-tool.html