Why do you want to add one more for filtering? just add a flag to the first object list.

const router = [
    {
        path: '/hello',
        icon: 'hammer',
        name: 'hello',
        title: '',
        children: [
            { path: 'index', title: '', name: 'hello_index' },
            { path: 'index1', title: '1', name: 'hello_index1' }
        ]
    },
    {
        path: '/hello1',
        icon: 'hammer',
        name: 'hello1',
        title: '',
        children: [
            { path: 'index2', title: '2', name: 'hello_index2',meta: {noshow:true} },
            { path: 'index3', title: '3', name: 'hello_index3' ,meta: {noshow:true}},
            { path: 'index4', title: '3', name: 'hello_index4' }
        ]
    },
    {
        path: '/hello2',
        icon: 'hammer',
        name: 'hello2',
        title: '',
        meta: {noshow:true},
        children: [
            { path: 'index4', title: '4', name: 'hello_index4' },
            { path: 'index5', title: '5', name: 'hello_index5' }
        ]
    }
]

it would be nice to judge that the noshow in meta is true, at run time.

violence screening, all we can do is to optimize the degree of violence;

let router = [
    {
        path: '/hello',
        icon: 'hammer',
        name: 'hello',
        title: '',
        children: [
            { path: 'index', title: '', name: 'hello_index' },
            { path: 'index1', title: '1', name: 'hello_index1' }
        ]
    },
    {
        path: '/hello1',
        icon: 'hammer',
        name: 'hello1',
        title: '',
        children: [
            { path: 'index2', title: '2', name: 'hello_index2' },
            { path: 'index3', title: '3', name: 'hello_index3' },
            { path: 'index4', title: '3', name: 'hello_index4' }
        ]
    },
    {
        path: '/hello2',
        icon: 'hammer',
        name: 'hello2',
        title: '',
        children: [
            { path: 'index4', title: '4', name: 'hello_index4' },
            { path: 'index5', title: '5', name: 'hello_index5' }
        ]
    }
]
let routernone = {
    '/hello2': [],
    '/hello1': ['index2', 'index3']
}


router = router.filter((route, index) => {
     if (routernone[route.path]){
        if (routernone[route.path].length > 0) {
            route.children = route.children.filter((child)=> {
                return routernone[route.path].indexOf(child.path) <= -1
            })
            
            return true
        } else {
            return false
        }
    } else {
        return true
    }
})


console.log(router)

let router = [
    {
        path: '/hello',
        icon: 'hammer',
        name: 'hello',
        title: '',
        children: [
            { path: 'index', title: '', name: 'hello_index' },
            { path: 'index1', title: '1', name: 'hello_index1' }
        ]
    },
    {
        path: '/hello1',
        icon: 'hammer',
        name: 'hello1',
        title: '',
        children: [
            { path: 'index2', title: '2', name: 'hello_index2' },
            { path: 'index3', title: '3', name: 'hello_index3' },
            { path: 'index4', title: '3', name: 'hello_index4' }
        ]
    },
    {
        path: '/hello2',
        icon: 'hammer',
        name: 'hello2',
        title: '',
        children: [
            { path: 'index4', title: '4', name: 'hello_index4' },
            { path: 'index5', title: '5', name: 'hello_index5' }
        ]
    }
];
let routernone = [
    { path: '/hello2'}
];
let routernone2 = [
     {
        path: '/hello1',
        children: [
            'index2', 'index3'
        ]
    }
];
router = router.filter(item => {
    return routernone.findIndex( i => item.path == i.path) == -1;
}).map(item => {
    
    let temp = routernone2.find(i => i.path == item.path);
    if(temp){
        item.children = item.children.filter(ii => !temp.children.find(iii => iii == ii.path));
    } 
    return item;
});