removing an image on my macbook pro screen

Please remember to include the version of Mac OS you are running.

To get to the picture on your desktop, click the black Apple icon on the top left of the screen and select System Preferences. (This is where the version of Mac OS X comes in, because System Preferences is different from one version to the next. But lets assume its the most recent.)

Click Desktop & Screen Saver, then the Desktop tab.

On the left, you can select a new desktop - a photo, a solid colour, or whatever.

You can try to find the picture through the screen saver.

On the left you will see the names of the folders the screen saver accesses. Find the folders on your hard drive, and delete the file.