How can I recursively delete all files of a specific extension in the current directory?

You don’t even need to use rm in this case if you are afraid. Use find:

find . -name "*.bak" -type f -delete

But use it with precaution. Run first:

find . -name "*.bak" -type f

to see exactly which files you will remove.

Also, make sure that -delete is the last argument in your command. If you put it before the -name *.bak argument, it will delete everything.

See man find and man rm for more info and see also this related question on SE:

• How do I remove all .pyc files from a project?