add collection.delete

weed/storage/erasure_coding/ec_shard.go

@@ -64,6 +64,10 @@ func (shard *EcVolumeShard) Close() {
 	}
 }
 
+func (shard *EcVolumeShard) Destroy() {
+	os.Remove(shard.FileName() + ToExt(int(shard.ShardId)))
+}
+
 func (shard *EcVolumeShard) ReadAt(buf []byte, offset int64) (int, error) {
 
 	return shard.ecdFile.ReadAt(buf, offset)