how to remove css property using javascript?

You have two options:

OPTION 1:

You can use removeProperty method. It will remove a style from an element.

el.style.removeProperty('zoom');

OPTION 2:

You can set it to the default value:

el.style.zoom = "";

The effective zoom will now be whatever follows from the definitions set in the stylesheets (through link and style tags). So this syntax will only modify the local style of this element.

removeProperty will remove a style from an element.

Example:

div.style.removeProperty('zoom');

MDN documentation page:
CSSStyleDeclaration.removeProperty

div.style.removeProperty('zoom');