Can’t deactivate this plugin

Hi, I’m having a bit of trouble with this plugin. Everything is working ok, except my events page only shows a few events and then when you go to next event, it says there are none, then when you go back, they all show up.

So I asked The Modern Tribe people for support, and they sent me a list of things to try. First I am meant to deactivate all of my plugins, one by one, to see if there is a conflict. The trouble is, I can’t deactivate this one without getting ‘the white screen of death’, and then I have to change it to the 2016 theme to get my dashboard working again to reactivate the plugin. I can only get it to deactivate if I first deactivate the Events Calendar and The Events Calendar shortcode plugins first. Any ideas on what might be causing this conflict? I’d really like to use this color functionality.

I do have this code in my child theme (functions.php):
teccc_add_legend_view( ‘list’ );
teccc_add_legend_view( ‘week’ );
teccc_add_legend_view( ‘day’ );

Could that be causing an issue?

thanks for your help!