Hey TXC CLUTCHER,
If you forget your PIN, you won't be able to access your files.
If you want to use it again, try clearing the data of Googlefiles app and then it allows you to have safefolder back.
As of now, there is no current safe folder password recovery option. But in a future version they will get that in place. I suggest you to SUBMIT FEEDBACK about what you are expecting in Google files.
Thanks and have a good day.