I cannot obtain my installer code and am trying to switch to another monitor company. If the Installer Lockout is Enabled, I may need to use a panel unlocker, right?

Have you tried to download a manual online, or contacting the old company? Most time the new monitoring company can help you unlock/disable the old system also. Cutting the power and removing the backup battery disables it too.

Assuming you are not trying to unlock it to use it ever again.

Have you tried to download a manual online, or contacting the old company? Most time the new monitoring company can help you unlock/disable the old system also. Cutting the power and removing the backup battery disables it too.

Assuming you are not trying to unlock it to use it ever again.

I do wish to continue using this unit but can't get the Installer code from the monitoring company (who will soon be my ex-company; as I am attempting to switch to a different company). I have the manual and will try the procedure to default the main panel, which will only work if "Installer Lockout" is disabled. If it is enabled the manual states the hardware default will not work. Any suggestions? Thanks.

Call DSC. Unless the equipment is owned by the monitoring company it's your device.
Every DSC manual is available online as well and every device can be reset to original factor startup specs. What is the monitoring company telling you?

https://www.askmehelpdesk.com/home-safety-security/how-do-reset-master-code-dsc-pc1832-547438.html

Your best bet is get the new company to do it as they will have the resources and knowledge to reprogram your unit.

I'm not sure what your expertise or time is, but it just may be faster to buy a new panel. They are priced quite reasonably and you can start from scratch with your own codes. Like I said it depends on your ability to make the swap.