to reset Batocera connect it by the PC using the CMD command then in the CMD write
ssh root@batocera
afte it will ask for the password enter linux after it connect put this command
/etc/init.d/S31emulationstation stop
and after that this one
/etc/init.d/S31emulationstation stop && mv /userdata/system /userdata/system.old && reboot
it will reset Batocera to default setting without removing the Roms folder but you have to check and re-config any other setting you change it to change it again
check this how to do the Factory reset
https://wiki.batocera.org/troubleshooting#factory_reset