It is highly recommended that you uninstall any previous versions of XL Fortran before you install XL Fortran V10.1. If you use the xlf_install utility to install the new version to the default location (/opt/ibmcmp/), it will remove the old files for you.
xlf_install will detect the presence of a previous version and will require that you uninstall it before it proceeds with the installation.
Before you use the xlf_install utility to install and configure XL Fortran V10.1, use the pre-installation checklist in Table 4 to ensure that all prerequisite conditions are satisfied.