clearing select using jquery

use .empty()

 $('select').empty().append('whatever');

you can also use .html() but note

When .html() is used to set an element's content, any content that was in that element is completely replaced by the new content. Consider the following HTML:

alternative: --- If you want only option elements to-be-remove, use .remove()

$('select option').remove();

$('option', '#theSelect').remove();

If you don't care about any child elements, e.g. optgroup, you can use empty()...

$('select').empty();

Otherwise, if you only want option elements removed, use remove().

$('select option').remove();