What are special permissions in Linux?

SUID is a special permission assigned to a file. These permissions allow the file being executed to be executed with the privileges of the owner. For example, if a file was owned by the root user and has the setuid bit set, no matter who executed the file it would always run with root user privileges.

How do I get rid of chmod gs?

To remove the setuid and setgid place a 0(zero) in front of the three permission bits: chmod 0777 /path/to/file.