How would I disable the minimap in Xcode 11?

Open a code file, such as *.swift, and press the second from the right button in the top right corner. Then click on Hide Minimap:

In newer versions of Xcode, this has changed and now looks as follows:

Navigate to Adjust Editor Options (at the top right corner, to the left of the Add Editor Below button) and uncheck Minimap (or press ^⇧⌘M).