The .snapshot directory is using up all my disk quota.

The .snapshot area is not counted as part of your disk use and is very useful to you as it allows you to potentially restore your own accidentally deleted files.

See the ZFS Snapshots.

The amount of disk space that you are being assessed for is the result of a unix command (e.g. while on lectura) of the form

      du -sk /home/<username>

detailed accounting within your home directory can be accomplished with commands:

      cd
      /usr/bin/du -sk  ./.??*  ./*  |  sort -n

If you are getting Over Quota messages for your 'home' directory it is not because of the .snapshot area.