Hide and Show Browser Tabs
The tabs of the Browser window give you access to every level of your model, from the root nodes and their entire contents in the 'Project' tab through selected Packages and their structure in the 'Context' tab and the elements in an open diagram in the 'Diagram' tab, to the detailed design of a single element in the 'Details' tab of the Inspector window. However, in any one work session you are unlikely to sweep across the full spectrum of your model structure, and it is probably more convenient to refine your work area and the objects listed to show the portion of the model and the type of structure you need to work on.
You can do this by hiding the Browser window tabs that are of less relevance to your task
For example, you might set up a skeleton project structure of Root nodes, Views, Model Packages and Packages, for which you initially would be working on the 'Project' tab and - for the lower levels of the model - the 'Context' tab. You would not need to use the 'Diagram' tab and could hide it.
Conversely, you might have set a large diagram to open automatically when you log on to Enterprise Architect, and spend the whole session working on the elements of that diagram, so you could hide the 'Project' and 'Context' tabs, and just work on the 'Diagram' tab, and/or on the 'Details' tab of the Inspector window.
Hide and Show Tabs
In the tab bar of the Browser window, right-click on the tab you want to hide, and click on the 'Hide Tab' option.
To restore any hidden tabs to the tab bar, right-click on the bar and select the 'Show All Tabs' option.