You can unlock all the locked columns/fields on a form by opening the developer console (CTRL + SHIFT + I) and pasting this in the console and running it:

Xrm.Page.data.entity.attributes.forEach(function (attribute, index) {
    let control = Xrm.Page.getControl(attribute.getName());
    if (control) {
      control.setDisabled(false)
    }
  });