You can put the form orientation to vertical. This will still display the label next to the checkbox.

or you can add some css to you project

@media (min-width: 768px){
  .checkbox {
      margin-left: 0 !important;
  }
}

Or you can use the set attribute widget https://appstore.home.mendix.com/link/app/5958/

Dom Query = .checkbox

Attribute: class

Value: col-sm-offset-0 

Append: true

I ended up creating this class

.ap_nooffset{
  [class*="col-sm-offset"] {
    margin-left: 0px;
  }
}