Removing required fields from order form

As part of the whole GDPR compliance thing I’ve been thinking about which fields my customers fill in when ordering. The main one that stands out is phone number. I never phone my customers and have no use for the data. I’ve even put a little note above the field that says to fill it with “any old rubbish”!

Is there some way to just remove that field? Having it record a default value would be fine (to avoid compatibility issues).