Checking in from Iowa and I have the option here too when I hit the customize button. I do have to scroll down a bit?
You might try uninstalling and reinstalling. If on android, clear your settings before the uninstall. The mcdee app does tend to be kind of unpredictable.
If that doesn't work, send an email to them. I actually did email on some problem I had and they responded pretty quick with a temp workaround and fixed it later.
Don't know how I feel about this. I already get sick of the security prompts every three days to manually enter my passcode. If Google starts just deleting them and making me redo them might just fucking go back to the passcode. Hope it's optional or it at least prompts you before deleting an old one. Not really trusting Google get it right.