Remove a workspace from GNOME Shell

In Gnome-Tweak-Tool you have the Menu Workspaces. Select Dynamic Workspaces -> Workspaces can be created on demand, and are automatically removed when empty. With this Option when you close the program from Workspace 3, then this workspace will be removed. I hope this will help you.

If you have "dynamic workspaces" instead of "static workspaces" enabled, an empty workspace at the top or middle of the list will automatically go away once you switch to another workspace.

But if you have GNOME extensions like "Auto Move Windows" or "Put Windows" enabled, this won't work. These extensions change the dynamic workspace behaviour to only remove empty workspaces at the end, not at the top or middle.

If you disable these extensions, you'll see the intended behaviour.

Install:

$ sudo apt install gnome-tweak-tool

Run:

$ gnome-tweaks

It can also be found in the (Arc) menu under Utilities as "Tweaks".

Set number of workspaces to static 1: