filter rules

please help me :cry:
when i add filter rules in firewall it works but when remove it, router must be reboot to this rule does not work. what reason?
for example :
chain=forward
dst.address=80.191.164.231
protocol=icmp
action=drop
this rule works fine, but i remove it ,again ip address 80.191.164.231 do not ping as long as reboot the router