All fields are optional. If, for example, you don't specify an eventKey, the key of the event is not modified.
Have a look at the docs for creating an event to know how tableBookingConfig works.
socialDistancingRulesetKey is the UUID which identifies a social distancing ruleset. You can get that key by retrieving the chart for the event.
By passing in the empty string as socialDistancingRulesetKey, you remove the social distancing ruleset from the event.