Hi Sonja,
You may have already taken care of this, but we did this on our site a different way that may work well for you. In the top navigation, go to My Sites>Network Admin and then use the left navigation to go to Settings>Custom Admin Bar. Disabling the WordPress icon and menu from the top navigation is the last item on this page. Also, if you want to replace it with something (for example, we replaced it with a link to our homepage so that anywhere a user was on the network they could always get back to home), just fill out that info in the first 3 items (1- enable custom entry, 2-enter the text that you’d like to have in place of the wordpress icon, 3-choose or enter the URL for where you would like this text to link to). That’s it!