In CentOS 7, you can follow these steps to disable and turn off the firewall.

1. Check Firewall Status

Use the following command to check the current status of the firewall:

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sudo firewall-cmd --state

If the output is not running, it means the firewall is already turned off.

2. Turn Off the Firewall

If the firewall is still running, you can use the following command to stop it:

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sudo systemctl stop firewalld

This command will stop the firewall service.

3. Disable the Firewall

To prevent the firewall from starting automatically at system boot, you can use the following command to disable it:

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sudo systemctl disable firewalld

This will disable the firewall service so that it does not start with the system.

4. Verify Firewall Status

Finally, you can use the following command once again to check whether the firewall has been successfully disabled:

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sudo firewall-cmd --state

If the output is not running, the firewall has been successfully turned off and disabled.

Please note that disabling the firewall may weaken the security of the server, so use it only in a testing environment.