How to remove mailgun from this template

[annis-souames]

It's been few days that I'm trying to do that but with no success, I verified my heroku account by adding a credit card, and then when I try to install this template through the deploy button it tells me that Mailgun couldn't be added and I need further verification, when I process to further verification, heroku doesn't support my phone number (which is more of a heroku issue).

How can I totally remove Mailgun from this template, I tried to remove from app.json but with no success :/ , Other plugins seems to work, I received an email from JawsDB successfully.