What's the equivalent terminal command for removing users/groups from a folder recursively? When I remove a user or a group permission from a folder and all its children files and folders, this is what I do:


Right click the folder
Click "Get info"
Unlock the padlock (typing my admin password)
Remove users and or groups
Press "Apply to all enclosed items" and confirm


How can I do this from the terminal?
You would use the chmod command, with the -a flag to delete access control list entries, and the -R flag to do so recursively.

For example: 

$ chmod -R -a "admin allow read" foldername

would make all files in foldername read-only for the admin user (because you're removing the "allow read" property for "admin".

$ chmod -R -a "joe allow delete" foldername

would prevent user joe from deleting any file in foldername.

To add properties back, use +a instead of -a.

For more details and examples, see the chmod manpage, or this article.