You can only delete local trophies (without syncing with the server).
To do this, clear the contents of the folders
ur0:user/00/trophy/conf/
ur0:user/00/trophy/data/
ux0:user/00/trophy/conf/
I may try the new ram site, and download more RAM to my Switch. Not sure if ddr3 is the right ram
for it tho. Edit- no it uses floppy Ram, just like @AncientBoi