[BScout]

Yes. I delete them all the time (and I especially don't keep them when archiving or sending a session to someone else.) Pro Tools rebuilds them. If you have one that large, it must have been there for a long time while you've had multiple sessions in the same folder. All the sessions in the folder will keep adding to it when you bring audio files into your sessions which is how it keeps growing.
If you have sessions in different folders, the WaveCache will be separate in each folder so a single one of those files won't get so large. (not that helps overall with space -- I just run a batch script to delete all WaveCache files and session backup folders when I archive)