A control primarily for the setting of the default values of parameters used in a dashboard, to reset all parameters to their default settings, is currently not built into the product. 

As a workaround, use a sheet as the reset button and configure parameter actions to set the parameters back to their default values.  A sample packaged workbook and a video on Step 3 is available in the Attachments section of this article.

Workaround for clearing all parameter changes with one button

To reset the parameter action change at one click do the following:

1. Add a new worksheet [Reset]

(1) Create a calculation field [Reset(Label)]  
"Reset"
(2) Create a calculation field [Reset Parameter]
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(3) Add a [Reset] field to the Text Marks card and add a [Reset Parameter] field to the Detail Marks card

2. Move to the Dashboard

(1) Add the [Reset] sheet to the dashboard
(2) On the menu bar click on [Dashboard] > [Actions]
(3) Click on [Add Actions Button] > [Change Parameter..]

(4) Add a parameter actions like below and click on [OK] button to save the change.
Name: Reset Category Parameter
Source Sheets: Reset
Target Parameter: Category_Parameter
Source Field: Reset Parameter
Run action on: Select

(5) Click on [Add Actions Button] > [Change Parameter..] again 

(6) Create a parameter action similar to step2-(4) to clear sub category parameter action and click OK button to save the changes.
Name: Reset Sub-Category Parameter
Source Sheets: Reset
Target Parameter: Sub-Category_Parameter
Source Field: Reset Parameter
Run action on: Select

3. Test the Solution

Click on Category and Sub-category to select the items on the dashboard and then click on the "Reset" button to clear the changes.
**Please refer to the Step3_verification.mp4 for step3.