Hi@akhtar,
There are two ways to delete an image. Let's discuss one by one
$ openstack image delete <image>
 Deletion of images is permanent and cannot be reversed. Only users with the appropriate permissions can delete images.

- 
Select the appropriate project from the drop down menu at the top left.
 
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On the Project tab, open the Compute tab and click Images category.
 
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Select the images that you want to delete.
 
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Click Delete Images.
 

Hope this will help you.
Thank You