The process of removing infected files from a time machine disk is tedious, as the files themselves cannot be directly removed. Instead it requires removal within the TIme Machine client, which maintains integrity of the backups.
Instead what one must do is find the path to the file on the computer's main drive (the one that was backed up) identify the date that the infected file was backed up, and then go into Time Machine and "delete all backups" for that file at that date.
It would be great if there was a direct way to instruct Symantec Endpoint Protection to expunge all backups from the Time Machine archive and have SEP interact with Time Machine to finish the job.