One problem with Emergency Lighting Units is the lack of off switches. Battery life could be saved by disconnecting the lead from the battery, but this could prove difficult. They are not designed for portable use and so lack the customary amenities. They can be awkward to carry.
Removing a unit, if the power is actually out, can be very easy: one simply lifts the unit up over the retaining screws and away from the wall and cuts the wires. But there are often complications, in a gymnasium the Emergency Lighting Units will be fitted with protecting cages that must be removed first.
In cinder-block buildings, the unit is often wired from the ceiling. If this is the case, there will be conduit coming down that surrounds the wires. This is usually attached by a clip and a screw, which need to be removed before any progress can be made.