According to the documentation https://learn.microsoft.com/en-us/azure/databricks/repos/git-operations-with-repos
"Local branches in Databricks cannot be deleted, so if you must remove them, you must also delete and reclone the repository."

Creating and throwing away local branches is fundamental to git, it encourages experimentation and allows to switch from incomplete WIP to work on something more pressing, then switch back. The ability to delete local branches should be added to the Git Folders functionality in Databricks. Having to delete and reclone the repo is an unacceptable workflow as there may be WIP which would be destroyed by the repo delete.