Users can choose to hide certain toolbar buttons by specifying the "toolbar" attribute in the JSON from project properties.
1) Press the Project Properties trigram
2) Select "Edit JSON..."
3) Add the below attribute to the JSON.
The value "false" will hide the button from view. Only add the code for buttons you wish to hide. If a button is not referenced in the toolbar attribute, it will default to showing.
Note: There a few buttons that cannot hidden with this attribute. If you wish to hide "export" or any of the other buttons not included in the list above, please contact firstname.lastname@example.org.