That means you are needing to clean up the Backup folder Microsoft uses for "Corrupted" applications/games. The steps to fix this requires Administrative access, and using the command prompt to erase each folder one by one.
- Start an administrative command prompt
- change the directory to "c:\Program Files\WindowsApps\MutableBackup"
- Run the takeown command to recursively take ownership of the complete folder and files for phantasy star online 2. Just as a heads up, The folders you are wanting to clear out start with "100B7A24.oxyna".
- Use the rmdir command to recursively delete the each folder containing "Corrupted" copies of Phantasy Star Online 2
NOTE: These Instructions do not include Instructions on what parameters to pass to the commands, but more information about the commands are gained by passing "/?" to the command.. So for example you can read the information on the commands using the following: