how do I remove a discount so I can apply another?

I have a teacher discount applied to my account (haven't worked there in 10+ years), but was recently told a military discount is better.  I am approved for the military discount, but cant apply it to my account until the teacher one is removed.  ATT says they cant remove the teacher discount, it needs to be done by the school.  The school doesn't know how to remove it.

Any ideas?