How can I clear (unset) custom dimensions from Google Analytics?

Question

On the "Thank You" page from an ecommerce transaction, I have used the Google Analytics tool to log the transaction. As part of this, I have used the 'set' feature to add some tracking data:

ga('require', 'ecommerce');
ga('ecommerce:addTransaction', {
    'id': '123456',
    'affiliation': '',
    'revenue': '9.99',
    'shipping': '1.11',
    'tax': '0.00'
});
ga('set', {
    'dimension5': 'Mr',
    'dimension6': '1968',
    'dimension7': 'G4'
});
ga('ecommerce:send');

This is all working fine. However, I have a search box on the sidebar of all pages, which I also track using Google Analytics. Normally this behaves perfectly, but if a user has just completed a transaction and uses the search box on that page, the custom dimensions are included in the details of that event.

How do I clear the custom dimensions completely? The API notes don't say, and the only reference I can find on a Google search recommends setting them to the empty string. This at least gets rid of the unwanted data, but the custom dimensions are still logged.

Answer 1

The correct way to get rid of them is to set the dimensions to null immediately after making the ecommerce:send call, like so:

...
ga('ecommerce:send');
ga('set', {
    'dimension5': null,
    'dimension6': null,
    'dimension7': null
});

This will remove all reference to them from the 'collect' query string.