Hide Profile Icon in Menu

Hello,

I want to use another membership tool than the one installed.
Therefor I would like to hide the profile icon from the menu (right side).

It’s working when I make the changes to main.css directly

.account{
        display: none;
/*	float: right;
*	display: block;
*	margin: 23px 20px 0px 0px;
*/
}

But I’m afraid this will be overwritten with the next updates.

I created temp_css.css and included it into the style.css of the theme.

The content is as above but I can’t get it to work.
I am using the same CSS File for other additional changes to a plugin and it is working fine only hiding the profile icon doesn’t work.
The custom CSS is in the same folder as main.css

Do you have any suggestions or maybe a simpler way?

Best,
Leon