Guided access locked my iPhone

iPhone 5 running 6.1 is stuck in guided access on MMS app. Asks for password which we forgot/don't know.

Hardware buttons are disabled, but I can restore the phone (pressing lock and home screen buttons). This restarts the phone but I merely get a glimpse of the lock screen when the phone goes instantly to the MMS app and a message appearing letting me know guided access is enabled.

In the forums I read about using iCloud to put phone on lost mode, which did let me lock the phone but upon entering the code I assigned through iCloud the phone goes into the MMS app once again locking up via guided access.

Not sure what more I can do before resorting to restore the phone altogether. Any input on this will be appreciated. Thanks!