knockout.js - knockout binding how to remove an attribute -

let's have html element

<element testattribute='a'></element> 

i know can pass value of testattribute using binding this:

<element data-bind="attr: { testattribute: 'a'}></element> 

but how can remove attribute through binding. if original value

 <element testattribute: 'a'></element> 

my end result should

<element></element> 

the attr binding in ko remove attribute if value false, null, or undefined. so, if bind against observable , set 1 of values (not empty string), attribute removed.