Enable & Disable SELinux

Enable & Disable SELinux on CentOS :

Disable SELinux :
Run on terminal

# echo 0 > /selinux/enforce

or

# setenforce 0

No need to reboot using above commands but when system will reboot SELinux will be enabled again.

Enable SELinux :

# echo 1 > /selinux/enforce

or

# setenforce 1

No need to reboot using above commands.

Permanent Solution (Disable SELinux ):
Open file /etc/selinux/config
change SELINUX=enforcing to SELINUX=permissive 
or 
SELINUX=enforcing to SELINUX=disabled
Reboot the system.
It will disable the SELinux permanently.

Check status of SELinux

# getenforce

Output is :
Disabled

Another command :

# sestatus

Output is :
SELinux status:                 disabled