Local Admin User -- deny additional local admins ?

How can I do something like the below "DESIRED"
solution without allowing step #6+ to happen since
I want to FORCE users to login as POWERUSER when doing
installs to help prevent accidentally installing
something without being aware of it (i.e. virus) ?

Server = Windows Server 2012 R2 with AD
Client = Windows 10 Pro
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Current
 1. user gets error message when
    trying to install something
 2. user calls me
 3. I DameWare into machine
 4. I login to Windows 10 Pro as me
 5. I do the install
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Desired
 1. user gets error message when
    trying to install something
 2. user logs into Windows 10 Pro
    as "USER=POWERUSER, PASS=something"
 3. user does install
 4. user logs back into
    their regular account
 5. install works
 6. user does above desired step #2 again,
    doing the below to grant their
    USER=LastNameFirstInitial ADMIN
    rights all the time
       ** Control Panel
       ** Administrative Tools
       ** Computer Management
       ** Local Users and Groups
       ** Groups
       ** Administrators
       ** Add
       ** USER=LastNameFirstInitial