For example, i want to add 1-14 levels as a main category and any% and 100% are subcategories.

Extra Variables/subcategories, then add new variable, name the variable whatever (I'm guessing you'll want it to say "category" for any% and 100%) once you do that add new value, which is where you put Any% and then add another to have 100% for two separate subcategories, also make sure you check off the box that says use as subcategory

Also disclaimer if you are putting a subcategory over a pre-existing category with runs in it already those runs will "disappear" but still be on the site, I'm not sure if you're planning on doing just that, but if you are you can hit the mango colored button below your values which sets all the runs in the category to the default value(subcategory) which will allow you to edit them all and separate them to their respective subcategories if anything gets mixed up

Thank you ;)