You can create symbolic links to both files and directories, first make sure you are in the directory where you want the link to appear.
To create a symbolic link:
$ ln -s /path/to/file-name linked-file-name
$ ln -s /shared/NGS/data/ngsdatafile.fastq ngsdatafile.fastq
To delete a symbolic link, make sure you are in the directory with the link:
$ rm linked-file-name
If you delete the soft link the data will still be there in the original location. Of course, if you delete the actual data in the original location the link will be lost, as will your data.