There is a specific way you should forward visitors to the new site.
I would suggest putting up your site at companyname.com . Then you would use a
301 redirect to forward all of your traffic from wearcompanyname.com to companyname.com
The 301 redirect will let search engines (and visitors) know that the content has permanently moved from wearcompanyname to companyname.
If you have a blog on your website, you can put up a quick notice that lets people know about the web address change. Then be sure to change all of your marketing materials, business cards, etc.