I am not a member of the Joomshaper team therefore, with all my desire, I could not fulfill your request even if it will possible. But this is generally not possible.
You should understand how the template works in Joomla and in general in any CMS. How works general CSS code and CSS files of whole site. You can not turn off its styles in a separate module. You can only override this for separate module using your own CSS code (in custom.css file) by changing the properties and their meanings as you need.
It is for this in the modules, in menu items and in many other places in Joomla there is a field to add your own class.
And even if it will possible to disable template's styles for separate module, you would not get anything from this. Your module will turn into a simple HTML marking without any styles (unless the module has owned styles in its code). Since the template's styles are the only styles that are used on the page. It is impossible to get styles from Cassiopea if Helix Ultimate is assigned to the page and vice versa