To make a one level drill down bar chart in tableau, we can use parameters or actions.

Parameters: 

Let’s say, the goal is to make a drill down bar chart using superstore from category to subcategory. Every time a category is clicked, the table opens up the corresponding sub category.

First make a parameter filled with the top level variable. In this case, it is the category.

Then make a calculated field to replace the sub category.

Place the values into rows and columns.

Now we need to create a parameter action to change the parameter every time a category is clicked.

Now you have a drill down bar chart using parameter actions:

Sets:

How can we make a drill down bar chart in Tableau using Sets?

First, make a category set.

Then make a calculated field with a similar format to that of parameters.

Place the new calculated field into the rows:

Finally make a set action to change what is in the set.