There are many reasons as to why apps may need to be blocked on devices. Thankfully, this can easily be done by using a Restrictions MDM Profile.
Creating the MDM Profile
To create this MDM Profile, navigate to the Catalog > MDM Profiles page and select New. Then, search for "Restrictions" and choose the option that appears.
Next, go into the Apps tab and look for the highlighted setting:
To begin incorporating apps, click the check box on the right-hand side and begin adding. You can search for native or app store apps, but if the app is not present on either option, you can manually enter the Bundle ID by clicking Add Bundle ID.