Hide the Tinymce button in frontend to not admin users

Hi Tom and thanks for such an awesome plugin, it really help me to improve my site performance. I’m just having a little problem with the frontend and You can see it here.

This is a popup window for a logged out or a logged in user, but not admin, to invite friends so it calls tinymce but the wpsocialite button for that case should be only to admin users.

I tried to hide it with:

.mce-toolbar .mce-btn-group .mce-last {
display: none!important;
}

but it didn’t worked. Any advice for how can I hide this button?

Note: WP Last version (3.9)

Thanks in advance!

https://www.ads-software.com/plugins/wpsocialite/