STEP-1: Go to WooCommerce-> Settings and Enable taxes. Then click on save change.
STEP-2: After enable tax you will see tax option and click on it.
STEP-3: After click tax you will get some options more important option is tax class. There are Standard , Reduced rate, and Zero rate. You can delete , update and add new tax class without Standard . You can delete existing class by removing line and add new class by adding new line in “Additional tax classes” option.