Read this and specifically the "Also be patient" part.
Elasticsearch will never assign a primary shard and its replica to the same node, so if you only have one node you will never be able to allocate any configured replica shards. Ways to remove the unassigned shard would be to add another node to the cluster or set the number of replicas to 0 for all indices.
If you have unassigned primary shards, have a look at this blog post.