Deleting every 3rd field using awk

I have a file whose format is like the following

350,2,16.2,195,2,8.0

every 3rd column of this file should be deleted. How can i achieve this

tried with the following

 iostat -D -l 2 | /usr/xpg4/bin/awk ' NR>2 { for (i=0;i<=NF;i++)if(i%3==0)$i=""};'

but no luck

awk -F"," '{print $1","$2","$4","$5","$6}' a.txt >> newfile.txt

echo "A,B,-,C,D,-,E,F"| awk -F"," '{for(i=1; i<=NF; i++){if( i%3 ){print $i}}}'
A
B
C
D
E
F

Another approach:

awk -F, '{$3="";sub(",,",",")}1' OFS=","