How to UnInstall Intel Compilers versions 11 and 12

If you need to reinstall Intel Compilers, you need to uninstall first,

Composer XE 2011 Update  2:
#  /opt/intel/composerxe-2011.2.137/bin/uninstall.sh --default

Compiler Pro 11.1: 
# /opt/intel/Compiler/11.1/038/bin/ia32/uninstall_cproc.sh --default

For more information, see Intel Compilers for Linux Versions 11.1 and 12.0 Silent Installation Guide