Hide excluded folders from tree in IntelliJ IDEA

The answer is close, in the Project gear menu:

PS: Yes, it's a self-learning post

Also, you may have switched on the Show Excluded Files option. If so, use Shift + Shift and type excluded and do the obvious thing.

Right click at the directory you want to exclude to mark it as excluded, , and then uncheck the Show Excluded Files option.

1: Intellij IDEA > Preferences.

2: Go to File Types.

3: Add *.iml and *.idea to the Ignore files and folders list box at the bottom of this window.