Proxy reset for Optionlist

I have a list of options like

{
   id: 'city_id',
   suggest: common.table.sizing(),
   header: [_tables.city, {content: 'selectFilter', compare: common.table.stringCompare}],
   minWidth: 120,
   options: 'getOptions->Cities',
   sort: 'text'
 },

the customer proxy getOptions (cities in this case) is:

 webix.proxy.getOptions = {
    init:function(){
      webix.extend(this, webix.proxy.rest);
    },
    $proxy:true,
    load: function(view,params){
      let source = this.source;
      let result = webix.storage.local.get(source);
      if(result){
          console.log('load '+source+' options from cache');
          return result;
      }
      let url = '/'+source+'/getOptions';
      return webix.ajax(url,function(text,data){
          console.log('load '+source+' options from server');
           webix.storage.local.put(source, data.json());
       });
    }
};

It will not load from server but from cache somewhere and I can not update while databases content has been changed! How can I reset this proxy so it will be forced to load from server again!??

like a proxy reset or something. Is it possible that I didn’t understand the concept for the proxy mechanism at all?

Please for help and have a nice xmas
Michael