Rename / move .idea folder for IntelliJ project?

You cannot rename the .idea directory; IntelliJ IDEA always reads project files from the directory with this exact name and cannot be changed.

Moving is possible. The location and roots of the content of modules in IntelliJ IDEA are completely independent of the location of the project itself. Because of this, you can create a project in a directory that does not contain any code, and set up modules with content roots pointing to the directories where the code resides.