OP you are correct to stop corruption in a nation that corruption has eaten dip into them will be a very big problem for a newly elected president.
Especially a nation that corruption has reached
there grassroot, being there small town and
villages.
However the president can stop the corruption and
make the nation work well again but it will take time.
But the problem is that if the office of the president
is 4 or 5 years according to the constitution of that
nation is impossible for him to totally stop it in that
period of time but he can reduce it with that number
of years he or she will be in office.

No Nation on earth is corruption free and so all the
leaders in different nations should keep fighting it
till they end it totally or reduce it to 5 percent out
100 percent.
I most also congratulate some leaders that has tried
there best in reducing the corruption in there nation
and for those leaders that are still not doing anything
about stopping corruption in there nation please start
now.