Tomcat 7.0.42 + MySQL 5.5.21 Portal master GIT ID: 236b2907e649e43aae9363a7b7156adf3a117bfb.
Steps to reproduce:
1. Admin > Pages > Logo. (You can not see a "Delete" button.)
2. Choose an image and save it.
3. You can see a "Delete" button right now.
4. Click "Delete".
5. You will notice that the image disappears.
You should not see the "Delete" button after you click "Delete". It should seems like when you first click the logo button.
You can see the logo disappears, but the "Delete" button also exists.