Payment methods

I’ve been working on a Website that was handed to me and my team by the former administrator. He didn’t tell us anything about it and it is also our first project with drupal so we basically started from scratch. We have set the Website up locally using xampp and we have full backend admin access.
The Website represents a Dance school and you can book and pay courses on the Website. There are two payment methods available: Payment by Bankaccount, and PayPal. The latter must be disabled and not be available anymore.
I have looked at countless Forum entries but can’t seem to find the right solution so as a last resort I decided to make a Forum Post myself.
Thanks in advance for any solutions or links to already Fixed Forum posts that handle my problem.

Drupal version: 


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