When upgrading to Standard or Premium, consolidating Workspaces is a good way to unify your users and boards so that you don't pay multiple times for each user.
Changing a Workspace name
Change a Workspace name and short name at any time by clicking the pencil icon at the top of the Workspace settings page. “Name” is what will appear on that page, and “Short Name” is the string that will show up in the Workspace URL (e.g. trello.com/workspacename).
Creating a collection (optional)
If you want to organize your boards into Collections, you can Create a new collection. Collections can be created before or after you move boards into the desired Workspace. If you need to edit a collection’s title or delete it, click the “+” icon under one of the boards and the pencil icon next to the collection you’d like to edit.
Prepare Workspace settings
If you don't have any Workspaces upgraded to Standard or Premium, upgrade the one with the most members. You should also verify that guests are allowed on Workspace boards from the Workspace Settings page.
Go to the first Workspace you’re going to merge. If there’s an option, click “Show other members’ private boards” so you can be sure to move all boards over. This option won’t show up if there aren’t any private boards you’re not a member of. If you’re moving over a board that you don’t want everyone to have access to, be sure the icon on the far right of the title says “Private”.
If it says “Public” or “Workspace-visible”, you can change the board to “Private” by clicking that phrase and selecting “Private”.
To move a board:
Open the board and click the … in the board header to open the board menu.
Click on Settings > Above Workspace, click on the name of your Workspace
Select the Workspace you want to move the board into
Once the board has been moved, you can add it to a collection from the mean Workspace boards page. Click the “+” under the board.
Move Workspace members
Once you’ve moved over all boards from a Workspace, you can move over the members. Go to the Workspace you’re merging to find the usernames of your Workspace members. On the main Workspace, click “Invite Workspace Members” to add each member. If you’re unable to click the member to add them, they are already a member of the Workspace.
Delete the empty Workspaces
Go back to the Workspace you’re merging and remove that member from that Workspace by clicking “Remove” to the right of their name, to keep track of who’s been added.
Once everyone has been added removed from that Workspace, you can delete it. Go to the Settings tab and click “Delete Workspace?” at the bottom of the page to remove the Workspace from Trello.