Codes can be deleted, alarms themselves CANNOT be recoded.
There is NO such thing as a master fob.
The ai606 can store up to 8 codes, 4 from the normal key fobs, and another 4 from
"tag keys".
Deleting "keys"(fobs) and "tags", is done from the systems programming function, this you DO need to have a good grasp of, as it cana ffect even the most basic operation of the alarm is it is done wrong.
If you pm me I can send you details of how to do, plus all the "clock" switch positions so you can adjust as you like the arm/disarm beep/volume, auto door lock etc etc.
For obvious reasosn I won't put this is general print, my advice if at all unsure just pay a toad dealer £20 or so, will have to wait for it but will be done with no messing up.
Toad were 100% wrong to tell you about auto delete, as if it has less than 4 stored it will just add as extra key number, like you found out.

tabetha