Following these steps will disable edit html access for all users except for admin.
First, switch to the core database.
Next, open the security editor on the launchpad.
In the security editor, choose the Sitecore Author role. If you have customized your roles, be sure to select the appropriate role here.
Deny “Read” on the following items.
You can configure different complexity levels for the rich text editor in Sitecore. Based on the one you are currently using, find the “Edit html” item and deny read for on that item.
When you are complete, these options are removed.
