Saving disabled and cleared fields on an Edit form - should blank the field on the database

I’m a bit stuck on how to “save” disabled fields in CakePHP 3.

Based on front end rules, on an Edit form, a field that previously had data is now blanked and disabled. However, when the form is saved. The previous value is still there, it’s not cleared.

Is there a setting or similar (in entity for example), that in this situation the field will be cleared on the database, to match what happened on the front end?

Currently, I will have to make it readonly and clear the value on the front end.