UNIX for Dummies Questions & Answers

Hi,
I got big problem.
a line contains like this:

Hell "A,B,C", how to delete A or B or C by using sed or other tools？
I do not have any idea.
Many thanks.

Code:

echo "Hello ABC" | sed 's/B//' 
# or
echo "Hello ABC" | tr -d 'B'

Hi,thanks anyway
but i want to have like this results:
Hell "A,B,C,D" ----> after delte A get Hell "B,C,D"
Hell "A,B,C,D" ----> after delte B get Hell "A,C,D"
Hell "A,B,C,D" ----> after delte C get Hell "A,B,D"
Hell "A,B,C,D" ----> after delte D get Hell "A,B,C"

---------- Post updated at 08:52 PM ---------- Previous update was at 08:33 PM ----------

Hell "A,B,C,D"
printf "enter the letter you want to delete："
read LETTER
-----------------------------------------------
then get that results,