I'm pretty new to Blender, so sorry if this question is silly. I am trying to unwrap a model that I created, and in the process I created a few images. There is 'Render Result' as well as two untitled images I created. What are the purposes of these images, and how do I delete them. In another model I am working on, there are no options in the menu as seen in the attached image. Even 'Render Result' is not present. From what I've gathered, 'Render Result' displays a blank, rectangular grid which does not show the UV map. The other two untitled images that I created on accident are solid black - and this color is not reflected onto the texture.
You can remove images(they are just simple images, not "UV images", you usually create a "UV Map" and it's not an image, but a set of coordinates in a 2 dimensional UV space for your model's vertices that are in 3 dimensional XYZ space so you can use a 2D image to color or texture a 3D model) in the Outliner set to Blender File mode by right-clicking and choosing Delete:
Or by shift + left-clicking on the x in the Image Editor after you have opened the image. This will not completely delete it straight away, but will clear it's users meaning the image will not be saved with the file and will be gone the next time you open the file. The 0 before the name of the image indicates that it has no users and will not be saved. If you use the image somewhere else, like for example as a texture in some material, this action will also break things there as you will have a missing picture there.
What are the purposes of these images[?]
You are responsible for coming up with the purpose of the two image you have created, because you chose to create them. They can be used as textures, masks, you can paint on them or bake some material properties to them or do whatever you want with them.
The Render Result is meant to store current render when you want to render your scene. You should not worry about its existence too much and it will get created when you render something even if you delete it.