What is the best way to change a website address?
We have 2 websites on WordPress. The first one is redirected to second one. All the contents are in the second one. As part of our branding initiative we want only one website address and want to transfer all the contents from second website to the first one.
Moving the content from one website to another when you are using Wordpress is simple. There are plenty of cloning programs out there for this. we use "Wptwin". This program will let you make a clone and move it to the new domain in one go. It is a simple program to use as they have lots of videos but after the first time you will not need them anymore it is that simple. (I am not the owner or getting paid for this software or advise).
As for duplicate content one of the people mentioned above. This does not apply by your situation as there would be two different domain names. The duplicate content issue only arises when you have the same content on the same domain.
You have several options available to you if I understand your question correctly:
I maybe corrected but all you need to do is change the DNS records. If you are not to sure what to do ring your hosting provider. If your 2 domain names and hosting are all with the same provider this will be simple.
My recommendations are to create the new website address "duplicating" your current one but setting it to be no indexed/block search engine robots. Set it up with Google Webmaster Tools and Analytics as well - these should be under the same account as your current site.
After a couple of weeks, you need to go to your current website's Google Web Master Tools account and report a change of address https://support.google.com/webmasters/answer/83106?hl=en
Then redirect the old site to the new site. Remove the blocking and check all your page redirects
You should be fine.