Why do textures stick around in the editor? UV unwrapping a mesh with different object using some image textures has some issues. Specifically, in this case, I have created a table and UV unwrapped the main part(the one that is active below):


Even when I tab out of edit mode and select a different part of the mesh the texture sticks around in the editor:  


As you can see, a different object is selected, the UV slot is empty BUT the texture stays. If I UV unwrap it anyway, the texture is automatically applied to the mesh portions as so:


If I hit the new button:
 

Blender only has options for generated textures:


And if I hit the cross button, there is no user for the texture:

And therefore, I cannot unwrap.  

I haven't had much experience with UV unwrapping. What is this problem? Why does this arise? Is there a way to refresh the UV editor? How can I fix this?
To get rid of unused textures, you have to save and then reload your file. 

Either use "File - Open Recent - " or hit Shift+Ctrl+O and then hit Enter, since your latest save is usually in the first place of the list. 

If you want to get rid of a texture despite having it assigned, press Shift and hit the X button beside the texture's name in the UV/image editor Texture dropdown. 

Besides that, textures are kept around on purpose. This comes in handy when you are optimizing your workflow. And you are certainly able to unwrap a model without any texture at all.