If your site was created before December 13, 2018, follow these instructions to remove Google+ from your Settings block.
In the Administration area of your site, locate the data definition for the Settings block.
Edit the data definition in XML.
Locate the group for Google Plus, around line 55.
Remove the entire group for Google Plus, as shown below.
<group identifier="googleplus" label="Google Plus"> <text identifier="username" label="Username/ID" size="80"/> </group>