Thank you your post into the forum.
You do not need to remove registered servers. The upgrade from SQL Backup V5.4 to Version 6.3 is a two part process.
You will need to upgrade both the SQL Backup GUI and the server components.
So on the server that has a GUI and the only registered server is the local server, no problem simply upgrade the GUI and deploy the server componets to the registered server.
On the machine that has multiple servers registered. Upgrade the SQL Backup GUI and then deploy the Server components to each of the registered servers.
When you first re-open the GUI after upgrading it , it will bring a reminder box that the server components need to be upgraded. When you view the regsitered server, a cog icon will be displayed to the right of the server to indicate that an upgrade is available.
If you have already upgraded the server components for the registered server, there will be no cog icon to the right of the server name in the registered servers panel.
A new feature added to SQL Backup V6.3 is the ability to activate multiple servers, so if you have multiple servers regsitered into the GUI registered servers panel form the Tools menu ->Utilities ->Multi-server Activation.
This new feature maybe useful to you, as by applying SQL Backup V6.*, activation is set back to trail license and you will need to re-activate after upgrading.
This sticky forum post contains a link to a pdf document that contains upgrade instructions. It was originally written for upgrading to SQL backup V6.0/6.1 from previous versions. However the advice is still valid for you upgrading from V5.4 to V6.3:
http://www.red-gate.com/messageboard/vi ... php?t=9346