Very Interesting thing about Admin Logo

I don't know if any one have this experience with Admin Logo.  I realy hope someone know and explain to me.
I have chanced the logo of the Administrator area.  That is one one many things I changed.
Here is what I would like some help.
After not being satisfying with my result, I would like to start every thing from beginning. So, I delete Nop database, delete Nop folder. WDE's temp.
I download the complete new Nop Zip file to start with.  Every thing went as it should.  There is not thing wrong.
The thing I don't understand is when I log in to Admin area.  Here I see My own Test Logo.  I see it weir, so I delete every thing again and redo it.  Here is again, I see My Own test logo.  I check every images in the new Nop folder, but there is only Nob admin image is there.
My question is Where does it take My Own testing Logo.
Very much hope someone can help me to understand.
Thanks very much,

The only way it can get your test logo after deleting it is from your cache, you need to push ctrl-F5 to do a cache reset refresh and the logo should than update.

BK, I did that before.  It is quite wier with my understanding.  the place I think it might be related is Registry, Memory.

when we are dealing with web projects, all the information are being stored in catch and sessions..

To see the change, try re-building your project and then you will see changes you made