If you need to move a workflow state into a different type (for instance, moving a Ready for Development workflow state from the Unstarted to the Started type), you can do that by going to Settings > Workspace Features > Workflows.
Find the hamburger icon next to the workflow state you want to move (next to the magnifying glass icon).
To move the workflow state, click and hold the hamburger icon, then drag and drop the workflow state into its new workflow type.
Only workflow states with no active Stories in them can be moved. If your workflow state has Stories in it, you'll have to temporarily move those Stories into a different workflow state, move the workflow state, and re-assign the Stories back into the workflow state when the move is complete.