If the value is hardcoded in the source of the page using the value
attribute then you can
$('#attached_docs :input[value="123"]').remove();
or
$('#attached_docs :input').filter(function(){return this.value=='123'}).remove();
If the value is hardcoded in the source of the page using the value
attribute then you can
$('#attached_docs :input[value="123"]').remove();
or
$('#attached_docs :input').filter(function(){return this.value=='123'}).remove();