How to move branch in SourceTree into Folder?

You can rename this branch:

git branch -m feature-2 feature/feature-2

You can also create new branch and delete the old one:

git checkout feature-2
git checkout -b feature/feature-2
git branch -d feature-2

SourceTree seems to display "folders" for branches that have the same folder/structure in their branch names.

You should simply create a new branch called feature/feature-2 pointing at the same commit as your current feature-2 branch. Then push the new branch and delete the old one.

You can name your branches in a folder structure-like format and they appear as folders in SourceTree. For example you could name it as features/issue_1539 and SourceTree will display features as a folder.

https://answers.atlassian.com/questions/200282/sourcetree-categorize-branches