in message_const.inc (location: amxmodx/scripting/include/) you can find a function to destroy the followbeam
#define TE_KILLBEAM 99 // Kill all beams attached to entity
// write_byte(TE_KILLBEAM)
// write_short(entity)
so in code it should be:
Code:
public stopstr(index){
message_begin(MSG_BROADCAST, SVC_TEMPENTITY)
write_byte(99)
write_short(index)
message_end()
}