Please! How to delete old scan images? Not very techy!

I'm sorry. I don't know what you mean by "opening image" each time you open finder. Finder can be set to open to a particular folder or favorite. i.e All My files, Documents.

Do you mean you have a background image set for that folder? Where files and folders are sitting on that image?

Standard Finder open to Desktop

Are you referring to the entire Desktop background?

This is set in Apple Menu > System Preferences > Desktop & screensaver, Desktop tab. Select a new image from the ones listed.

To delete an old Desktop image you will need to work put where it is stored, when you click it in the Desktop settings it should list the filename which you can then search in Spotlight to remove the original file.

Finder windows also have an option to set the background image, set this by opening the Finder window, choose View menu > View options, reset the background near the bottom of that palette.

P.S.

Sorry if this is completely wrong, the terms you are using are not really clear.

If you've already changed your desktop picture, then you are done. The desktop image is loaded from a temp file that changes when you set a new one.

Just change it to something else if you have not done so.

Can you still see the image in the Desktop background settings?

If so select it & look for the filename in the window.

By default screenshots are saved on your Desktop.

If it was from a scanner, try making a new scan to see where that image get saved - it may be the easiest way for you to figure out where they get saved.

Also take a look inside your home folder > Pictures or perhaps the Home folder > Documents.

I may be missing something, but ; just drag it to the trashcan on the dock.