first of all, the interface looks like this
 
:
 1.elementUI
 2.: - 
 3.: - Mayabeque
 4.Mayabeque 
 
 
according to the normal logic, I deleted the country, and the corresponding province should be deleted automatically.
<el-select v-model="countryID" multiple filterable placeholder="" @change="loadRegion()">
    <el-option
        width="100%"
        v-for="item in list_country"
        :key="item.value"
        :label="item.name"
        :value="item.value">
    </el-option>
</el-select>    
{{countryID}}
<el-select v-model="regionID" multiple filterable placeholder="">
    <el-option
        width="100%"
        v-for="item in list_region"
        :key="item.value"
        :label="item.name"
        :value="item.value">
    </el-option>
</el-select> 
function of loadRegion ():
1:
1.
2.this.list_region = 
question : this.countryID is used to save the country selected by the user, but I don"t know how to judge. If the country deletes the corresponding province, it also deletes it.
