how do I delete all images from my computers
Some images on your computer are needed for your operating system, so be careful what you delete.
If you have images that you need to delete then try a free shredder program like File Shredder http://www.fileshredder.org/
What I will say though is that when you delete files from your computer, they are still available until the the location that they occupy on the disk is overwritten. This can take years and can still be recovered even after a format.
These shredder programs fill the deleted files location on the disk with 1's and 0's and over write the file(s) with these up to 25 times which is usual military standard.
This does not mean that the files cannot still be retrieved by forensic professionals.
just delete it all and you can formate your computer to be sure of it ^_^