You can do it by Sql but it not a recommended Way.
The backup which you perform using the AVVI or hyper-V agent will show "Snapshot full" irrespective if you select AOFO or not .The backup is a snapshot backup. When backing up using AWS you will see "Full" when backup is taken with AOFO not enabled.
Its Not true , Incremental back can start irrespective of the Full backup .
If there is not full backup job ran then the 1st incremental backup job is as good as a full backup Job.
Check if there any alerts ?
I beleive you can't remove the option if you have had the option installed in evaluation mode.