There is no fire hazard. You still should just cut an bury them. You should disconnect them at the source. Then you can cut and abandon them in the wall. Never leave an active wire in a wall.
Typo error fixedThere is no fire hazard. You still should not just cut and bury them. You should disconnect them at the source. Then you can cut and abandon them in the wall. Never leave an active wire in a wall.