How to change opmnctl port to 80

Note: In all below steps $WT_HOME represents Webtier installation location(Generally /app/Oracle/products/Middleware/oracle_WT).

1. Go to $WT_HOME/instances/instance1/bin and execute below command.
$ ./opmnctl stopall

2. Take http.conf backup from $WT_HOME/instances/instance1/config/OHS/ohs1
$ cp httpd.conf httpd.conf.bck

3. Open http.conf and change port number to 80(Just after 'Listen').

4. Go to $WT_HOME/ohs/bin and execute below commands.
$ chown root .apachectl
$ chmod 6750 .apachectl

5. Go to $WT_HOME/instances/instance1/bin and execute below command.
$ ./opmnctl startall