I like to have a subroutine to clear everything. I don’t know if this covers everything you need, but it will get you started:
on clearSelections()
set variableOne to ""
tell window "mainWindow"
set string value of combo box "embossingSelect" to "Choose from the list" --Change back to the default text
set current column of matrix "thisColumnSelect" to 1 --sets a radio button thta has one row of many columns back to the first button
set current row of matrix "thisRowSelect" to 1 --sets a radio button thta has one column of many rows back to the first button
set the contents of text field "thisText" to ""
end tell
end clearSelections
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