That's right, if you're on a mac(unix) you won't see .git in finder(the file browser). You can follow the directions above to delete and there are git commands that allow you to delete files as well(they are sometimes difficult to work with and learn, for example: on making a 'git rm -r ' command you might be prompted with a .git/ not found. Here is the git command specs:
usage: git rm [options] [--] ...
-n, --dry-run dry run
-q, --quiet do not list removed files
--cached only remove from the index
-f, --force override the up-to-date check
-r allow recursive removal
--ignore-unmatch exit with a zero status even if nothing matched
When I had to do this, deleting the objects and refs didn't matter. After I deleted the other files in the .git, I initialized a git repo with 'git init' and it created an empty repo.