Question about being under contract through a mega carrier.

I had a mega carrier pay for my CDL school and obviously I have to pay them back, however, I just offered a job from my mentor (he is a O/O through this mega carrier) and he is offering quite a bit more than the mega carrier is.

I don't mind breaking the contract and paying the loan back, but what would be the best way to go about it?

PS: I literally just finished my training today through the mentorship.