Save the settings and preferences by opening the 'Finder'. Access 'Library' folder in the user directory. Open the 'Preferences' and find the folder named as 'Adobe Photoshop settings'. The name may be a little different as it depends on the version of this software. Drag it to the desktop while holding Option key on the keyboard to copy.
Drag file that is named as 'Adobe Photoshop Paths' for deleting it. This file would be located in Preferences where you found Settings folder.
Access the directory of Applications and drag the folder of Adobe Photoshop to the trashcan. It would delete the current installation for making room for the new installation.
Insert the installation CD of Adobe into the optical drive or you can also double-click the file of downloaded installation to begin the installation process.
Enter your serial number and name on the window that appears for installation. You can find the serial number on back side of the case of installation CD or it would be e-mailed by Adobe to you. All the other information is optional that is displayed on this screen.
Read software license agreement, select the location that you would like the software installed to on the system and then click OK. Photoshop would install to the chosen directory automatically.
Return to the Finder and then navigate to Preferences folder in the user library. Drag folder of Adobe Photoshop settings from the desktop to Preferences folder. Click the 'Yes' for overwriting new default folder of Adobe Photoshop Settings that was created by you when you reinstalled the Photoshop.
By following the above mentioned simple steps, you can easily reinstall the Adobe Photoshop to your MacBook Pro.