The getenforce command will display the current SELinux mode of either Permissive or Enforcing. Use the setenforce command to change the SELinux mode. Issuing the command setenforce 0 will put your system into Permissive mode, while issuing the command setenforce 1 will return the system to Enforcing mode.
You must be logged into the sysadm role to change the current SELinux mode, see Section 7.3 for a discussion of SELinux roles.