To delete a non-empty directory on Linux when you receive a "directory not empty" error, you can use the rm command with the -r option to recursively delete the contents of the directory.
Here is an example of how to delete a non-empty directory called dir:
rm -r dir
This will delete the dir directory and all of its contents, including any subdirectories and files.
Note that using the rm -r command can be dangerous, as it will delete all files and directories in the specified directory without prompting for confirmation. Make sure you are deleting the correct directory and that you have a backup of any important files before using this command.