To close port 53 of the meditation operating system, the steps are as follows:

1. Log in to the Nios system.

2. Open the firewall settings and find the relevant setting options.

3. Find the setting option of port 53, which is located in the advanced options of firewall settings.

4. Change the status of port 53 to "Off" and "Disabled".

5. Save the settings and exit the firewall settings interface.