If an issue status is not being used in your workflow you can choose to either hide it or completely remove it from the status list.
The advantage of hiding it is that you can later unhide it easily if you want to start using it again, while if you know you will never use it it can be a good idea to remoe it completely.
You cannot remove a status that is being used though, so if you wish to remove it anyway filter on all issues with that status and change them to another status.
To hide a status:
1. Go Project - Settings - Statuses.
2. Uncheck the status you do not wish to be seen or used in the issue list.
3. Press Save.
To remove a status:
1. Go to General - Settings - Issue Configuration - Issue statuses.
2. To your right, press the red cross to remove a status.
3. A warning dialog will be shown asking if you wish to remove the status, press Yes.
4. The change is carrried out immediately.