To remove a cache completely, including the cache object, its cache volume and all space-optimized snapshots that use the cache:
# vxprint -g diskgroup -vne \ "v_plex.pl_subdisk.sd_dm_name ~ /cache_object/"
where cache_object is the name of the cache object.
# vxedit -g diskgroup -r rm snapvol ...
where snapvol is the name of a top-level snapshot volume.
# vxcache -g diskgroup stop cache_object
# vxedit -g diskgroup -r rm cache_object