If I remember correctly ours was mounted with staples. Only left a couple small holes that were covered with the velcro when we hung our picture. If yours appears to be glued you can try thin string, floss, fishing, or thread. Move from top to bottom, sawing back and forth with light down and outward pressure. Once the frame comes off you can deal with anything left behind.
04 Allegro 30DA, WH 8.1, Banks, 03 Honda CRV/2012 Jeep Liberty Jet, Brake Buddy Adv Select, 300watts Solar, 7 Group 31 Optima AGMs, 2000watt PSW inverter
"Philippians 4:11-13 KJV"