Is there a way to remove plugins in dashboard – where you cannot identify the slug by the plugins name?

I think what you’ll want to do is iterate over the $_GLOBALS['menu'] array. This should give you a list of all the items in the admin menu so you know what the hooks are that need to be removed.

There are more details and good information in this answer: https://wordpress.stackexchange.com/a/136064/9080

The appropriate hook/slug can be found in the array element with key 2, according to that answer.

You may also find this tutorial useful Customizing Your WordPress Admin