Not quite what you asked as this just does the current folder, but it is a simple method using basic scripting which you can learn from and build on:

#! /bin/bash

# Create an array of MKV files to process
# Assumes current folder, lists files and feeds them into a variable

files=$(ls *.mkv)

# Loop through the filenames

for filename in ${files[@]}

    do
        echo $filename
        mkvpropedit $filename -d title -t all:

    done

The mkvpropedit command featured removes the title and all tags which is what research suggests many people wish to achieve.

The function that feeds the array of files could include paths so would be:

files=$(ls */*.mkv)

Not sure this would handle files or folders with spaces in the names though.