Hi,
There are a few ways to disable the button action through customization. I believe the easiest way would be to disable the ability to execute by user role.
To do this you would need to copy and replace the current Method screen and edit this new screen. When editing, edit the "More Actions" button in the Additional Info section. Click Next on Step 1, and on Step 2, click the elipsis button as seen below:
When you click on that button, you are now editing the "Event", which is "Delete Customer". Step 2 on this screen allows you to set which roles have access to execute the event. Only the users whose role is selected on this screen will be able to execute the "Delete Customer" action.
There are other ways of achieving this, but this seems like the simplest to achieve what you are looking for.
Hope this helps,
- Adam