Just edit ES_Systems.CFG. This file controls what file extensions EmulationStation will make visible in its menus.
The file is found at /etc/emulationstation/es_systems.cfg
Search the file for “PlayStation” and edit the EXTENSION section to match mine:
<system>
<fullname>Sony Playstation 1</fullname>
<name>psx</name>
<path>~/RetroPie/roms/psx</path>
<extension>.bin .BIN .cbn .CBN .img .IMG .iso .ISO .mdf .MDF .pbp .PBP .toc .TOC .z .Z .znx .ZNX</extension>
<command>/opt/retropie/supplementary/runcommand/runcommand.sh 1 "/opt/retropie/emulators/retroarch/bin/retroarch -L /opt/retropie/libretrocores/psxlibretro/libretro.so --config /opt/retropie/configs/all/retroarch.cfg --appendconfig /opt/retropie/configs/psx/retroarch.cfg %ROM%" "psxlibretro"</command>
<platform>psx</platform>
<theme>psx</theme>
</system>
These changes make sure that .CUE, .CCD etc are ignored and adds other common disk image formats. Don’t worry, the emulator runs them all just fine.