#!/bin/bash

ROOT_DIR="/path/to/text/files/you/just/made/"

for year in "$ROOT_DIR"/*; do
    if [ -d "$year" ]; then
        for month in "$year"/*; do
            if [ -d "$month" ]; then
                cd "$month"
                for file in *.txt; do
                    pandoc "$file" --pdf-engine=xelatex -o "${file%.txt}.pdf" && rm "$file"
                done
                cd "$ROOT_DIR"
            fi
        done
    fi
done