I have a mac so I might be of some help.
1. In finder click 'go'
2. Click 'go to folder'
3. Type "~/Libaray" (without quotation marks) in the window that appears
4. Navigate to the folder "Application support" and open it
5. Find the minecraft folder in the application support folder.
6. Open the minecraft folder and navigate to the texture packs folder
7. Open the texture pack folder and delete the problem texture pack from there.