How to erase in sqlplus with backspace?
If you're using Linux/Unix, there's a way of making SQL*Plus loads friendlier on the command line - use rlwrap. It adds readline support to SQLPlus, allowing you to use the cursor keys to navigate to previous queries (it retains a history), and edit them when you've made a mistake.

Launch SQL*Plus with rlwrap -i sqlplus or add  alias sqlplus="rlwrap -i sqlplus" to your shell dot file (.bashrc/.cshrc/etc).  

To install rlwrap on RHEL 5.0 use the following commands:

wget http://download.fedoraproject.org/pub/epel/5/i386/epel-release-5-4.noarch.rpm
rpm -Uvh epel-release-5-4.noarch.rpm
yum install rlwrap
rlwrap –i sqlplus