I think this question is fine now, the input file is good enough after edit, I can fully understand what you ask for now.
With awk, you need learn to use 2-d array, it will simplify the code.
awk 'BEGIN{print "Instance id Name Owner Cost.centre"}
/TAG/{split($0,a,FS);a[4]=tolower(a[4]);$1=$2=$3=$4="";b[a[3],a[4]]=$0;c[a[3]]}
END{for (i in c) printf "%-18s%-26s%-14s%-20s\n",i,b[i,"name"],b[i,"owner"],b[i,"cost.center"]}' file
Instance id Name Owner Cost.centre
i-e1cfc499 Memcached
i-7f4b9300 Test_LB01_Sachin
i-c4260db8 Rishi_Win_SAML Rishi Pandey
i-fb5ca283 CLIQR-DO NOT TOUCH mataa 1234
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solved Error in shell script and how to write to a file [closed]