It's possible, yes but definitely not recommended. Especially since the end of full support for 6.3 is about a month away:
Essentially you would be following the same steps as an upgrade but going the opposite direction and there would be added compatibility considerations since the newer agent version won't be able to communicate with older collectors and such so these would need to be restarted or reinstalled depending on which bootstrap version they are on.
Is there a particular reason you are looking to downgrade two versions? Is there some issue - I would definitely say the better option is to try to resolve this as opposed to downgrading to something that you shortly won't be getting full support for.
Dear James, Christopher,
please note that running the opposite steps of the upgrade guide will not work. If you already had the new version running, most configuration files will be written with the new version and format 7.0, which the old version will not recognize.
So it will be expected that you will lose all your configuration data. Strongly advise against this.
As mention in another comment, please try to solve the issue first with support, this should be easier, safer and saves you from doing the upgrade again. Plus if we know about it we can fix it for you and other users!
Having said that, the only way to downgrade is to restore backups, from PWH, session storage and most importantly your migration archives. Or if you still have the old installation directories, to start those up again.
Obviously this means losing all changes and data since the upgrade.
Details can be found here:
When you rebuild the schema, all Performance Warehouse data is lost.
However, I am still confused why you roll back to 6.3?! Did you already create a support ticket to resolve the UEM voucher problem? This should be an easy one and you don't have the pain to switch back to an older version.
This is the ticket number SUPLIC-17375. The reason is that the UEM voucher had expired and was for 1yr. Currently the license i have is for the older version(6.3) yet i had upgrade it to 7.0.