You can rename and delete workspaces by going to Window | Workspace | Manage Workspace. This menu will allow you to rename and delete workspaces.

If you need to delete a workspace, click on it to highlight it and then hit the Delete button. To rename a workspace, highlight it and then use the Change setting name button. Type in a new name and hit Enter on your keyboard. Once you're done taking care of your changes, press the OK button.
Switching between our Workspaces is as simple as pressing two mouse buttons. Simply go to Window | Workspace and then click on the name of the workspace that you want to use. You might notice that Manga Studio comes with two workspaces already set up, as well. One of these is a Manga workspace and the other is called Illustration. I'd suggest loading those up and seeing if you like one of them to use for your own work. One of the great things about Manga Studio 5 is that you don't have to make yourself and your workflow work...