Instructions
Open "C:\Program Files" and click on "Valve," then on "Steam."
Find the folder named "Steam Apps" and open it. Locate the folder with your steam handle as the title. Open it and select the "Counter Strike Source" folder.
Click on the folder named "Cstrike," then open the materials folder. Locate the folder named "VGUI" and open it.
Open the "Logos" file. The data for the in-game sprays is in this file. Delete the files you no longer want.
Boot the game to make sure the changes have taken effect.