How Do I Force Change a URL / Permalink?

I have several URLs that have a number appended to them, like this one:

http://www.aur.edu/academics/international-relations7/

What I want it to be is this:

http://www.aur.edu/academics/international-relations/

(Minus the number)

But when I attempt to fix it, it always reverts to the number.

How can I purge the database so that the clean URL / Permalink is once again available?

Thanks,

Tim