If I told you that eliminating resentment is an easy task, I would lie to you. It is a process, and like any process, it requires following some steps.
TAKE AWARENESS OF THE CAUSE OF RESENTMENT
The first thing you have to do is realize and recognize that you are experiencing resentment, and of course identify what is causing it.
This is usually easy, because when you are feeling resentment you internally reiterate the cause of your disappointment.EXPRESS AND ASK
If you consider that the person who caused you pain may be open to help you resolve that feeling you are harboring, express assertively how you feel and how you expected to have acted.
Whenever possible, ask what you want me to do to correct the pain (usually apologize, ask for forgiveness ..)CHOOSE
Once the previous process has been completed, and regardless of whether the person has responded in a positive way to the previous step, you have to choose what relationship you want to have with that person, and here are two possibilities:
Follow your relationship with that person: in that case you choose to stay with the person and not with their behavior. If that were the case, you should support the person in the process of modifying that behavior.
Do not continue the relationship with that person
In both cases you have previously had to completely correct your resentment.