JSFiddle - React, Tailwind, and code Playground

JavaScript

var object_1 = [
    {'value': '9:00', 'text':'9:00 am', 'eventtime':'09:00:00' },
    {'value': '9:30', 'text':'9:30 am', 'eventtime':'09:30:00' },
    {'value': '10:00', 'text':'10:00 am', 'eventtime':'10:00:00' },
    {'value': '10:30', 'text':'10:30 am', 'eventtime':'10:30:00' },
    {'value': '11:00', 'text':'11:00 am', 'eventtime':'11:00:00' },
    {'value': '11:30', 'text':'11:30 am', 'eventtime':'11:30:00' }
],
object_2 = [
    {'eventtime': '10:30:00'},
    {'eventtime': '11:00:00'}
],
object_new = object_1.slice(),
temp = [];
    
for (var i=object_2.length-1; i>=0; --i) {
    temp[i] = object_2[i].eventtime;
}
    
for (var i=object_new.length-1; i>=0; --i) {
    if ( temp.indexOf( object_new[i].eventtime ) !== -1) {
        object_new.splice(i, 1);
    }
}
console.log(object_new);