How to untrack files in GIT

I accidentally commit some files that should not be tracked, e.g. folder .gradle, IntelliJ IDEA project file *.iml… Obviously that’s not good. Searching around, I found a thread in SOF, in summary:

• Step 1: git rm --cached <files/folders>
• Step 2: git update-index --no-assume-unchanged <files/folders>
• Step 3: Add to .gitignore

Sound good, but doesn’t work!

This is working:

• Step 1 (remove all from index): git rm -r --cached .
• Step 2 (add again): git add .
• Step 3: git commit -m "fixing .gitignore"