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Please try this formula in cell H7 of your worksheet.
=TEXT(VALUE(IF(LEFT($D7,3)="+62",MID($D7,4,20),$D7)),"""+62""0")
The backbone of this formula is in IF(LEFT($D7,3)="+62",MID($D7,4,20),$D7). This function removes "+62" if it is found in the original number. This is the part that would need to be expanded if you also encounter numbers starting with 0062 in column D.
The VALUE() function converts the string into a number, which removes any leading zeroes.
The outer TEXT() function, finally, converts the number back into a string (now without leading zeroes) and prefixes it with your country code.