• I removed all the listed items from Xcode's Window Menu → devices and simulators, which listed iOS 12 as their OS version. This is a long list, so use the quick-dirty AppleScript code given at the end.

• Went to iOS settings → Developer and cleared paired devices.

• Connected iPhone, unlocked it and chose "Don't Trust" upon prompt.

• Applescript click automation in Google Chrome browser?

• Run script in automator (without terminal) brew install cliclick

• Create a new (.txt) File in Finder - Keyboard Shortcut see this for using Automator + AppleScript.

Copy paste the Automator block to repeat the script, or use repeat feature of the code, or tie it with a shortcut.

-- Click “Xcode” in the Dock.
delay 0.0387
set timeoutSeconds to 2.0
set uiScript to "click UI Element \"Xcode\" of list 1 of application process \"Dock\""
my doWithTimeout(uiScript, timeoutSeconds)

-- 
delay 0.273133
set timeoutSeconds to 2.0
set uiScript to "click tool bar 1 of window \"Devices\" of application process \"Xcode\""
my doWithTimeout(uiScript, timeoutSeconds)

-- Click the “Simulators” radio button.
delay 0.059993
set timeoutSeconds to 2.0
set uiScript to "click radio button \"Simulators\" of radio group 1 of group 1 of tool bar 1 of window \"Devices\" of application process \"Xcode\""
my doWithTimeout(uiScript, timeoutSeconds)

-- Type “iPad Air” into the text field.

do shell script "/usr/local/bin/cliclick rc:252,252"

-- Delete
delay 0.88761
set timeoutSeconds to 2.0
set uiScript to "click menu item \"Delete\" of menu 1 of outline 1 of scroll area 1 of splitter group 1 of group 1 of window \"Devices\" of application process \"Xcode\""
my doWithTimeout(uiScript, timeoutSeconds)

-- Click the “Delete” button.
delay 0.267897
set timeoutSeconds to 2.0
set uiScript to "click UI Element \"Delete\" of sheet 1 of window \"Devices\" of application process \"Xcode\""
my doWithTimeout(uiScript, timeoutSeconds)

on doWithTimeout(uiScript, timeoutSeconds)
    set endDate to (current date) + timeoutSeconds
    repeat
        try
            run script "tell application \"System Events\"
" & uiScript & "
end tell"
            exit repeat
        on error errorMessage
            if ((current date) > endDate) then
                error "Can not " & uiScript
            end if
        end try
    end repeat
end doWithTimeout

• I removed all the listed items from Xcode's Window Menu → devices and simulators, which listed iOS 12 as their OS version.

• Went to iOS settings → Developer and cleared paired devices.

• Connected iPhone, unlocked it and chose "Don't Trust" upon prompt.