Modify a spelling mistake

Fixed a small spelling error

Change-Id: Ic201111640a55661e1b312ece7d797ff82eafe49
diff --git a/tempest/api/image/v2/test_images_negative.py b/tempest/api/image/v2/test_images_negative.py
index 14de8fd..f60fb0c 100644
--- a/tempest/api/image/v2/test_images_negative.py
+++ b/tempest/api/image/v2/test_images_negative.py
@@ -29,7 +29,7 @@
         ** get image with image_id=NULL
         ** get the deleted image
         ** delete non-existent image
-        ** delete rimage with  image_id=NULL
+        ** delete image with image_id=NULL
         ** delete the deleted image
      """