chmod 600 filename will do it;
or
chmod 700 if it is an executable.
Another way that is less cryptic is:
chmod go-rwx filename
- The “g” is for group
- The “o” is for others
- The “-” is for removing permissions
- The “r” is for read-permission
- The “w” is for write-permission
- The “x” is for execute permission.
For the sake of completeness:
- “u” is for user / owner
- “+” is for adding permissions