There is no any straight method to delete your Viber account all you need to uninstall your Viber application, Now again If you want to register your Viber account (after uninstall) , you don’t need to have another number to register it for the second time.
Just repeat this process http://www.viberdownload.org/how-to-register-viber again for your current number from which you got the registration for the first time.
As I described above it is multi-platform application. It is also available for the Desktop PC version, On that version you will also register your Viber account through your phone number.
And what happen if you deleted your viber account by error and you want to install again.
Easy, you should read again our post about Register Viber App, and make all the steps included in the short guide. You are Done!