Why some numbers are added to url of ajax object and how to remove them?

Just use cache : true. jQuery will automatically add a timestamp to the end of the URL for you, making sure that ajax requests are never cached.

from jquery docs

Default: true, false for dataType ‘script’ and ‘jsonp’
If set to false, it will force requested pages not to be cached by the browser.
Setting cache to false also appends a query string parameter,
“_=[TIMESTAMP]“, to the URL.

$.ajaxSetup({'cache':true});

Jquery Ajax Docs