code: public void invalidateDisk() {
          if (!diskMode.equals(DualCacheDiskMode.DISABLE)) {
              try {
                  dualCacheLock.lockFullDiskWrite();
                  diskLruCache.delete();
                  openDiskLruCache(diskCacheFolder);
              } catch (IOException e) {
                  logger.logError(e);
              } finally {
                  dualCacheLock.unLockFullDiskWrite();
              }
          }
      }
docs: Remove all objects from Disk.