Use the Below 3 steps to remove an entry from the IPtables :
1. Check the Entry :
iptables-save | grep IP
2. Check the Line number :
iptables -nL -v –line-numbers | grep IP
3. Suppose the Line number is 100, Use the below command to delete the entry :
iptables -D PREROUTING 100
note : here I used the PREROUTING chain. Change it accordingly using the output from step 1.