Do temporary licenses need to be removed before installing any permanent license?
No. Administrators can simply overwrite licenses by applying a new license key with either the "License Apply" command or through the Administration Suite.
As of Release 3.4, licenses can be applied in the Administration Suite System > Utilities > License page.
There is no trace of the earlier license upon completion. Be careful not to overwrite a permanent license with a temporary one, unless that is the desired behavior.