In the left pane select your workspace
In the right pane click on Customize Workspace
Expand Menus in both panes; you may need to expand the Partial CUI Files to get to the different CUIs that are loaded.
In the left pane check/uncheck the menus you want shown/deleted, they should show/update in the right.
You can arrange the order by dragging and dropping in the right.
Note: there is a maximum of 24 (25?) menus allowed on startup
Don't forget to apply and save your workspace.