How to Hide a Question in the Registration Form of an Active Event but Keep the Data Associated with Existing Attendees

At times, you may need to remove a question from the registration form of an active event. The question could be something like selecting a t-shirt size, but you need to order the t-shirts now and don't want to let people who register in the future to get a shirt. 

Note, this option requires the Advanced Registration Forms upgrade.

So, you could remove the t-shirt size question from the question group so that it is no longer be asked in the registration form, but that would remove the question and answers from the records of the attendees you already have registered as if you never asked that question. 

Instead, you can hide a question from the registration form, and keep it visible in the registration records by making the question an Admin-Only question.

To make a question an Admin-Only question, navigate to Event Smart > Registration Form > Questions > Edit Question, then select the Admin-Only option:

Then save the page.

Now, that question for your existing attendees will stay in place. But future attendees will not see that question in the registration form.